The old Four Stallion idea of having a good imported stallion in hand for the use of pony breeders was revived in 1918 and 1919 when the Polo Pony stallion, Field Marshall, was hired by the Lyndhurst Society. He was a 14.2 hh chestnut by Marechal Niel by Rosewater, to whom most of the best ponies of several breeds go back, ex Polo Queen dam Black Welsh mare. He certainly imparted quality to his stock but he had a wide white blaze extended over his muzzle, stockings behind and white off fore fetlock and so introduced extensive white markings, inherited by his grandson, Brookside Spitfire, and Brookside David, his great grandson. By 1920 it had been decided that outside blood should be limited to stallions from the other Mountain and Moorland breeds, so his place was taken for one year by a Fell pony Weardale Hero. However, one well known Judge wondered if any of the progeny of these two stallions would ever, in fact, run on the forest and opinion was still that those ponies with the most actual Forest blood did better than the progeny of the imported ponies, so the Stud Book was closed in 1935.

The Polo Pony Stud Book (later the NPS) admitted Mountain 8 Moorland ponies to Vol: 5 of their Stud Book. There was a different section for each "district" and the New Forest was defined as "difficult to give the exact description but the best are 12.2hh to 13.2hh. If taken off at weaning and done well for their first two winters often make 14.0hh to 14.1hh. They sometimes have an apparent lack of bone but what there is should be the very best quality, the feet are wide and well formed, they are often considered goose rumped but their hocks should be all that can be desired. In colour, they range through every variety but dun is rare and few, if any, piebalds, the flea bitten greys which are very common show strong traces of an Arab cross. The shoulders, though not always what might be desired in point of depth are almost invariable fine and well laid. It is a great characteristic of the Forest pony to be always gay and alert and though extremely good tempered and docile when fairly broken they are quite indomitable till fairly cornered, the true Forester is never sulky."

The first NF Stud Book was produced in 1910, the work proved too much for the Hon Sec Mr Coote, who complained the Commoners only sent in their applications at the very last moment! So Mr Kershaw was appointed and paid a salary, This volume contained 118 stallions divided into stallions that have run on the Forest and pony stallions standing in the New Forest Parliamentary District, 356 mares whose dams must have run on the Forest for at least one season as a 3 year old or upwards and a few un-numbered geldings. The first President and Chairman of the Lyndhurst Society, Lord Lucas, defining pony character says:–

"There is a certain quality in ponies which entirely distinguishes them from horses, "Pony Character". It is almost more mental than physical. It is, as the name conveys, more a question of character than size, make or shape. A pony can be bigger than a cob, yet a true cob has horse character and a pony has pony character. It is one of the first things a judge looks for and of its importance, every judge is agreed. I believe I can tell it when I come across it but am at a loss how to describe it. I believe it is a combination of many things, none of them except the head, being purely physical. It is that which enables a pony to live where a horse would starve, to trot over ground where a horse would walk, to thrive on work that would kill a horse, of equal strength, to be clever where a horse would be stupid, to be a friend where a horse would be a servant. All these and a thousand other similar attributes are comprised in "pony character". If we are to breed ponies we cannot afford to risk anything that would lose it, for it can be lost. A few crosses with a horse, although he himself be of pony origin will soon destroy or completely impair it."

Speaking of cross breeding, he was opposed to crossing with horse blood because of the loss of pony character, but "TB blood is in a different category for there can be found thoroughbreds with their full share of pony character and besides they are the cream of horse flesh and there never was any milk spoilt by the addition of a little cream. I believe TB blood will improve any pony, though from considerations of hardiness it should not come in undiluted, the same applies to Arab."

He found the faults of all Mountain & Moorland ponies to be the same when visiting the West Country to find new blood. However, he was very impressed with the stock of the Welsh Stallion, Dyoll Starlight, but complained his stock was so sought after they were very expensive which showed the value of a Stud Book in establishing blood lines. He bought 4, Picket Pole Star, Picket Grayling, Picket North Star, Picket Starlight, who when he had run on the Forest for a year or two, managed to look more Forest than Welsh. He also acquired Picket Hermit, a docked bay cob by a TB, Timothy, grandson of Hermit, who had won the Derby in a snowstorm, out of an Exmoor Mare. He became very popular because in spite of his TB blood his stock did very well on the Forest. Picket Hermit sired Dainty IV, who, having won the Childs' Working Hunter Class at the Breed show 6 times, also bred a number of foals and became the ancestress of Brookside David. Up to 1989 she has 1492 registered descendants.

David sired Oakley Jonathon and when blood typing was introduced for stallions, Newmarket pointed out that some of this line had a blood group previously only found in TB's.

One of the entries in the second stallion section is Tommy Dodd I, 13.0hh chestnut foaled 1896 by Yuresson (one of the Arabs the Queen lent the Verderers), ex Exmoor mare by Katerfelto, known in the Polo Pony Stud Book as Cathephelta, which confuses computers. His descendants are still around. Only two volumes of the NF Stud Book were printed because World War I intervened. Mr Kershaw was called up and acting Hon Secs took over and all registrations were sent to the NPS, which continued to register NF ponies until 1960. By then it took so long and was considered too expensive, so a Local Register for stallions to run on the Forest and be shown at Burley, in the non hand fed class and to run in the Point-to-Point was started. This record was not printed so no one could look ponies up to find their breeding, so, in 1960 the first red New Forest Stud Book appeared and has been produced annually ever since.

Unfortunately, registrations lapsed during World War II. When the Pony boom afterwards arrived many were registered, Forest Horse ex. Forest Mare, whose breeding must have been known on the dam's side. This is particularly frustrating with the Mudeford ponies. Mudeford Bluebell, for instance, who won show classes and races has no registered descendants today, and neither has Dolores, a daughter of Griselda, who Mr. Burry bought from Miss Blackmore, although he kept the ponies and registered many after the War, nearly all Forest Horse ex. Forest Mare. Miss Jackson was one of the very few owners who kept up their registrations so it vas lucky Mr. Burry bought Brookside David from her. Lord Lucas thought 13hh the size to aim at, as smaller ponies did not sell so well being in competition from Dartmoor, Exmoor and Wales and he did not think much bigger would live on the Forest, so for a while 13.0hh was the limit on brood mares at the show. The stallions in section 2 could be up to 14.2hh and so presently the height limit for both became 14,0hh, increased to 14.2hh in 1955. It was finally agreed that every registered pony should have a registered dam but an appendix register, for ponies known to the Agisters to be of pure Forest blood be included.

Forest mares, the progeny of mares bred on the Forest, who could have been registered, but were not, ran from Vol:8 to Vol; 32, but entires were excluded after Vol:8, Harmonization of Stud Books within the E.EC demand that the definition of a New Forest Pony should be "tracing only to ponies already registered in The British New Forest Pony Stud Book", so it had to go, along with the First Cross register, now printed separately. Piebalds and skewbalds, all resulting from Shetland crosses, to produce short legged pit ponies, and kept because some buyers liked fancy colours, were banned in 1949. Blue eyed creams in 1970 because of the increased likelihood of breeding these from the untypical, very pale chestnut, failed palomino, dark eyed cream colts of this colour born in or after 1991 will only be accepted as geldings.

In spite of their mixed ancestry the ponies were becoming much more of a type due to the environmental influence of the rule that dams must have run the Forest, when this was removed private studs tended to favour different types from the genetic pool, so the Merrie Stud went for a more Welsh type, whilst the Knightwood ponies favoured the heavier Highland, and there was a considerable loss of type overall.

1912 first straight ridden class and Working Hunter Pony classes introduced.

Writing in 1910, the well known pony judge, The Rev T Dale wrote: "New Forest ponies have always been something of racehorses. In the 1880's there was a little grey mare that was never beaten. Her owner tried a TB cross, but declared the mare better. On one occasion he drove her 3 miles to the course where she won 3 races in succession, 6 heats in all, and drove her home afterwards. Her progeny, by Heron by Maccaroni were fast but not as fast as she was.

The NF pony is ideal for small holders having the weight and power to move a considerable load and the activity not to take too long about it and sufficient action to do it in style. They also show considerable stamina and weight carrying ability under saddle.

Three things are necessary to establish a first rate breed, time to blend the various strains of blood, in-breeding sufficient to fix a type both mental and physical, and long years of careful selection of the best breeding stock, and herein lies the value of the Stud Book."

Perhaps the above provided the inspiration for the 1911 innovations, the Non-hand fed Class for mares that lived continually on the Forest without extra Winter feed. The owners had to be prepared to find them and with the Agisters acted as "beaters" to drive the mares towards the judges, who were impressed with the action of the mares across the rough ground. Lady Lucas brought the picnic hamper out by car and a good time was had by all.

The following year the condition of the mares when judged in early spring was considered good, considering the prolonged drought of 1911. The ponies moved with freedom and style, the best conditioned mares had the best conformation, the best yearling and 2 year old seen were the produce of a 26 year old mare. The other innovation was the Point-to-Point, it may have been a revival, as there is an old tradition of cross country racing and Mr. Dale said the Forester has always been considered something of a Racer. Races had been held at Lyndhurst for years, premium winning stallions had often done well at them and, of course, sprint races were held at the Burley Show, where Lionel Edwards drew them in 1912, where it certainly looks as if the ponies were living up to their reputation of carrying a stone a hand. The new race was run on Boxing Day over a "take your own line" only disclosed at the meeting place, Boldrewood, rain fell in torrents and the ground from Millyford Bridge to Ocknell Pond was very rough in places. Of 16 entries 12 ran, the minimum weight was 11st with 71bs added to each inch over 13.0hh. No allowance for shoes. The top weight over the 31/2 miles was 13st. The entries were:–