Looking a bit harder at Frederick Huckle 14 b Biggleswade living in Keighley in 1871 there are three other Huckle lodgers living in the same house. Charles 20 and Sophia 19 were baptised in Biggleswade in 1850 and 1853, children of George and Martha, as was Frederick on 4 Apr 1856. Implying that unless it was a late registration the odds on the Dec 1857 birth are shortening.
The only chance of resolving this is to invest in birth certificates, which could be money wasted, but who knows.
Two IFs: if George Leggett who died in the Dec quarter 1855 and if Frederick Huckle born in the Dec quarter 1857 are both the correct people, then George couldn't have been Frederick's father. Which will make it all but impossible to find out why Frederick Huckle changed his name to Legate.