How can my partner sell his house which has a neighbouring house with subsidence?

[oceanauk]

My partner's been trying to sell his house. Over the last 18 months subsidence appeared and so came up on a survey when potential buyers started looking. However, it's the house next door with the probem but it's owned outright by an old lady with no money or house insurance. My partner has insurance but they will not do the work without the other house being repaired as it would just occur again. What can he do?? He can't sue either as again old lady with no money! He desperately needs to get rid of the house as he has his own business tied up in it and his ex is taking half and he will end up bankcrupt with months as he's running out of funds. He can't afford to sell it for less than the market value and having subsidence will leave him with a huge debt he can't cope with. Any ideas?

[buildersmate]

Bit of a tricky one, so don't know if this would work.
Try and persuade Building Control that the structure is dangerous to get them to put an enforcement notice on her?
The attached link comes randomly from Richmond Council because it expalins the scope of a dangerous structure.
http://www.richmond.gov.uk/home/environment/bu ilding_control/dangerous_structures.htm
The stupid thing is if the neighbour dug a huge hole in the garden into which the house threatened to subside, they would certainly do this. But a creeping natural phenomena? - not so sure.