I found a complete set of XJ-6 Series 3 (1979-1987) seats but done in Vinyl. Whoever did them added a lot of lateral foam support to the front sests, no more flattened seats and backs, they really "hug" you when you sit on them. I got tired of leather, the maintenance, the drying and splitting, too much work and hassle.

Yes leather smells great in old cars, vinyl has no smell. Just buy a can of artificial leather "perfume" and impress even yourself. Everything is "Artificial" nowadays anyway, intelligence, tik-tok, Made in USA, The Beatles started it with "Artificial Double Tracking" back in 1968.

I saw a set of S type front seats made by Watson in vinyl and was shocked; He cuts the foam to do what the factory never did, to encapsulate the driver !
Only trouble is you must ship the entire seats to him in Texas.

 

I have Series 1 XJ6 in mine - bolt straight in