In reply to FesteringSore:
Crikey, I could set that as an exam question.
The possibilities are as follows:
1. Mrs A transferred all her interest in the house to Mr A. It is his in every sense. End of story.
2. Mrs A has transferred only the legal title to Mr A and remains the beneficial owner (that means, the real owner, the true owner, the person entitled to proceeds of sale) of half of it. Mr A holds on trust for himself and Mrs A, half each. They share beneficial ownership and Mr A has the legal title, ie is the registered owner at the land registry.
But that doesn't tell us everything because we don't know, from those facts, what happened to Mrs A's half interest in the property on her death. There are two ways of arranging it.
2A the two own their half shares as "beneficial joint tenants" and Mrs A's half passes to Mr A on her death. So he owns outright and Mrs B gets nothing.
OR
2B they own as "beneficial tenants in common" in which case Mrs A's share survives as a separate entity.
Only in situation 2B does Mrs A's will pass a half share in the property to Mrs B.
SOooo Mrs B can only get anything if she can prove that situation 2B is what happened. And in practical terms the only way for her to prove that is from the terms of the transfer of the title to Mr A.
However, if 2B is the case, there ought to be a restriction on the title to the property preventing sale by a sole survivor. If there isn't such a restriction, then Mr A almost certainly owns outright and, again, Mrs B gets nothing.
Mrs B is the one who has to prove things. If there is no restriction on the register, Mr A almost certainly owns outright (although that is not completely certain. Equally if there IS a restriction that does not prove 100% that 2B is the correct analysis - only the terms of the transfer itself will tell you.
You can get sight of the register if you go to Land Registry's website, for a fiver or so.
L