Of course there wasn't going to be an investigation. Even if they wanted to make one Brown couldnt afford the scandal at the moment especially after bringing Mandy back into the fold.
I've been saying this for a while now, and especially with the housing market crashing the way it is wouldnt it be cheaper to just build or buy a block of housing or a big enough hotel and then add in all the security it would need to keep the MP's safe. No more need for second homes as they would have accomodation cutting that little fiddle and the security costs would be dramatically reduced as it would be a single building they would be protecting.