Did you consolidate many domains into the .com, or just move the domain over completely from .co.uk to .com? In which countries have your rankings dropped? I am guessing UK.
The backlinks you have are not on great websites. Have you tried to get listed in places like the UK's version of the Better Business Bureau? Put in some work doing some guest posting and I bet your rankings will go up.
My guess is that if your rankings have dropped mostly in the UK, that it's the loss of the .co.uk ccTLD, which is definitely not an insurmountable hurdle, just might take a bit more work.