dog defecating in house

Question
I have just fostered a retired greyhound a bitch of 4 years old.  Have had her for a fortnight now and when I leave her i come back and she has dececated on living room floor.  I dont shout or smack her and have tried ignoring her when i come in then when she calms down i play with her.  Also when i arrive home, which may only be 2 hrs, she calms down then pees over her bed.  I have another bitch greyhound older whos no trouble at all.  They are both walked daily for about 2 hrs so have plenty of exercise.  I dont want to return bonny but am at my wits end about what to do.

Answer
There's a great little booklet, not too expensive, with some great hints for house training older dogs:
"Way to Go - How to House Train a Dog of Any Age" by Patricia McConnell.
I'd suggest you get a copy.  Meantime, you can't expect her to know what you want her to do by just leaving her to her own devices, so do get the book before you think about returning her - this is probably solvable with a bit of supervision and training.