My recollection of the original BAH AS332Ls G-BKZE, G and H was that they were fitted with LHS brakes. Perhaps they were introduced at some point after delivery, assuming Border Reiver is correct?
G-TIGZ was the only ex BHL machine that found it's way back to the UK with BIH/CHC. The other two (X and Y) never did. The re-use of TIGZ was very deliberate by BIH management.
Re: G-TIGA, the re-allocation of any registration on a different airframe is not permitted in the UK. So it was not the Tiger Moth owner that spoilt the plan, it was CAA policy. Here's an extract from the CAA website:
"Any UK registration marks that are currently in use or have been registered in the past are not re-issued to a second aircraft to avoid any confusion. An individual airframe may have more than one registration mark in its lifetime, but a particular registration mark can only apply to one airframe."