Might have led you all up the garden path a bit there.

We didn't do the sewing of the covers.

I brought the covers from a company.
We had to strip the old covers.
Weld the seat frames up (as the leather covers are thicker you need longer retaining clips.
Make new retaining bars (as the old ones were not strong enough for the leather)
Then re-fit the new covers.

Was a really hard job actually, but the results are well worth it.

Matt.