10.7 Time Machine in 10.8

My iMac which backed up under 10.7 has just died. I want to access some of the files from my MBP which I have upgraded to 10.8.2, but on trying although I can see the files I get a "You dont have permissions......" message.

Have tried restarting, verifying the disk, etc, etc, without success.

Any help much appreciated