Haydon is known from the reference below. However the only Haydon listed in the trade directories for Fordingbridge is Frederick William Haydon who was a Chemist & Druggist and a sub-distributor of stamps. He was based in the High Street from the early 1860's until the 1880's. It is possible that taxidermy was a side line from Haydon's main occupation.
Reference: Kelsall, J E, Rev; Munn, Philip W: 1905: The Birds of Hampshire and the Isle of Wight: Witherby and Co.
'One case contains an adult honey buzzard (and a rough legged buzzard) with two young about a week old, which were taken in 1866, by a young man named Jack Peckham, who addressed the following epistle to Haydon, taxidermist, of Fordingbridge, from whom the specimens were purchased by Dr. Rake: 'Sir, - I know of two young honey bussards about a week old and what can you give me for them and likewise the old one send an answer by return of post and you will oblidge Yours obediently, Jack Peckham'"