Still not convinced they are shot but if they are you may as well go for sports cats if you have to replace them, will do the job at a fraction the cost unless you go second hand.
FTech suggested we look at the Cats but we hoping it was going to be a more common, cheaper option, we decided to start from scratch (plugs, coils, injectors, MAF, fuel pressure etc).
Having worked through these, all are working correctly. The thermometer arrived yesterday and the results are:
Engine running for a few minutes
R=180/30 (entry of Cat/exit of Cat)
L=150/100 (entry of Cat/exit of Cat)
Engine running for 10 mins:
R=320/200
L=290/270
The next job is to remove the Cats altogether as an extra check
I have spoken to Charlie at Prospeed and he can fit two new Sports Cats cheaper than standard Cats so that is a definite.
Will keep you updated, thanks for all your input.