Jane Louisa was certainly alive in 1939 when she and Leonard occur in the Poll Register.

Leonard died in 1944 and, I have his certificate and there is burial for Leonard at Witton Cemetery (Birmingham).
There is also a burial for Jane Louisa Phillips at Witton in 1951.
(Charles and Ann Many Russell are also buried there.)Leonard definitely died in 1963.
Therefore it seems pretty certain that Jane Louisa died in 1951 but I haven't been able to find a death index entry for her on FreeBMD, Ancestry or FindMyPast.

I had previously checked all sorts of combinations.