Breed History; . . . Now one of our rarest Native Breeds . . . . . .. ..According to Lewis Wright in the 1880's the AYLESBURY ducks should be of the purest white with a bill set well up on the skull and the beak almost in a line from the top of the head to the tip (similar to the Runner) and of a delicate flesh colour . Although pure ducks exist and are thriving as a breed most of those that the general public perceives as an Aylesbury are commercial meat crosses which are frequently pictured in children's story books, normally Cherry Valley Ducks. They are recorded as first brought into  America by Mr John Giles of Woodstock Conneticut specifically to create an American  meat bird and by 1864 are well known as a breed and a crossing parent. ( Domestic Poultry by Saunders 1868)
Historically they were walked from the Vale of Aylesbury to London (40miles max). Each of the inns they stopped the night at allowed the birds to be kept in large enclosed yards and in the morning the birdswere driven through a cold sticky tarry solution in a shallow ditch and then through a layer of sawdust. This made somewhat crude shoes to protect their feet for the day and the next night this was repeated with a charge of a few birds at each stop. The alternative was to try to camp on the common or 'waste' and stop the local poachers from removing a few for the pot.
The breed is thought to have further evolved during the early years of the eighteenth century by selective breeding of the common duck, usually brown or grey in colour but occasionally white. Breeders were aware that the London dealers had a preference for white plumage, the feathers being popular on the continent as quilt-filling and the pale pink skin of a plucked white bird is somewhat more attractive than the yellow of coloured ducks.
Prior to 1839, the ducklings if not "walked" were transported to London by packhorse or carrier's wagon, the opening of the branch railway line from Cheddington to Aylesbury in that year providing a boost to theindustry. J. K. Fowler, writing in 1850, tells us 'oftentimes in the spring, in one night, a ton weight of ducklings from six to eight weeksold are taken by rail from Aylesbury and the villages round to the metropolis'. Throughout the nineteenth century the main market for duck meat was provided by the wealthy people of London, very little of it being sold locally. Aylesbury ducks start laying eggs in early November, the two month old ducklings coming to market from February whereas the Rouen, its main competitor, began laying in February, coming to market as a six-month old bird in the last three months of the year. Peak season for Aylesburys was therefore late March and early April, the Rouen being geared for autumn and Christmas.
The number of establishments in Aylesbury began to decline after 1850 due to a number of factors, including the introduction of sanitary regulations which made duck rearing in cottages difficult. The deterioration in the quality of soil in Aylesbury following many years of duck raising has also been given as a contributory factor. 
 In 1901 Wright says In one respect the Aylesbury duck has somewhat changed during recent years. As we remember it in 860, and for some years
afterwards, it was not what duck-breeders term " keeled " underneath the body. By degrees this character was more and more cultivated, from a desire to increase the massive look of the birds, and at the present day the Standard describes and requires keel—the term is self explanatory— in exhibition birds.

For More Information : The Aylesbury Duck by Alison Ambrose,published 1991