Okay, I've just finished speaking with a very helpful lady at Ohme and checked all settings and it would appear that the car is limiting the charge. She mentioned that she has an MG and on 5kw lamp AC charger it slows at around 20 miles from 100%. Mine seems to be worse with soc 60% and 125 miles (from memory). Currently 70% 134 miles. Wife said it was at 7kw when first plugged in at about 2pm. Ohme has suggested running down to 40%, jump onto another 7kw charger and see what rates I get.
Last week end I jumped on to a Tesco 7kw charger. After one hour it only charged from 60% to 63% so I suspect this problem has been around for a while.
Also it has been queried as to whether the MG had had its update which it hasn't. So MG update is booked and take it from there.