hello
B&H serial numbers don't contain specific date information but they do run chronologically so can be used to help dating.
all the Hawkes & Sons Ajax i have seen (with the winged roundal badge) are in the range 8,000-10,000. this badge was used from 1927-30
after the merger the triangle badge was used 1935-1939. all the serial numbers on these drums fell in the range 10,000-20,000.
after the war the first oval badge was used and the earliest toms i had with this badge had serial numbers of around 21,000, i guesstimated these to 1946/7 taking into account some other factors as well
most of the 60's drums (including English Rogers) i have seen are in the range 90,000-120,000 (production ramped up because of the 'group explosion')
your drum is in the 28,000 region AND it is a piccolo model which in catalogues were being trumpeted as the 'new' thing around the early to mid 1950's following trends in USA. i think it was just to save on scarce raw materials.
at arm's length, i would estimate that your drum is around 1951-1953.
QUALITY
Boosey and Hawkes Ajax drums are indeed superb instruments and before 1969 some of their products were better than premier. however, some of the interior finishing quality is variable and is less pleasing.
please look here http://ukdrums.weebly.com/buying-tips.html for a couple of introductory notes about why the quality of UK drums is poorly understood.