Hang on - there's an underlying problem with some of the responses here, and it's to do with her age.
Age should not be a barrier here...in the same way that we shouldn't cap the age at which someone should be eligible for a transplant, we shouldn't discriminate against the elderly if they elect to undergo gender reassignment. If they they meet the criteria then they should have the op.
Besides - at 75, she may well have paid a lot more in NI contributions than the rest of us, so why not 'cash in' (terribly put, but I hope you get my drift).