On checking xe.com and a few other conversion sites I am finding that the tt rate seems lower than the rates on these sites which used to be the offshore rates.

Has the onshore/offshore rates ceased?

The difference between onshore and offshore exchange rates has lessened over the last few months, and seems today all but gone.

Checking x-rates.com has the Baht at 31.45 against the greenback, while Bangkok banks website indicates a 31.44 exchange rates for incoming TT transfers.

Although checking XE.com it has the dollar at 31.6137 or a difference of slightly over 0.5%....

Thai military bank is exchanging at 31.51 for TT's, or a difference with XE of a tad over 0.3%

Yeap, the on and off shore exchange rates have pretty much equalized with the lifting of the 30% Capital Controls this week. Whether the on and off shore rates stay pretty much equal will depend on what new and old polices/procedures the Thailand Finance Ministry and Bank of Thailand use to manage/stabilize the baht. I have no doubt there will be some innovative policies/procedures used.

Mid-market rates:

http://baht.thaivisa.com