I'm sure it is sinking a little on the left as I feel I am leaning a bit?I had this before on a Freelander which turned out to be a bad batch of foam and was replaced under warranty and never had a problem again. Anyone else had a problem?

The fact that you've had this on two different cars makes me wonder if you are sinking to the left.

Ha ha, the Freelander was the wife's car and it was a common fault

Nothing wrong with the base after all, had a look under the seat and under the right hand side cushion was a big chunk of shrink wrap obviously left over from manufacturing. Pulled it out and good as new