I'm guessing your car is more than about 10 years old, which could be why Jaguar have stopped selling them. You might have some luck at somewhere like Halford's or a local motor factors.
I helped a friend find some parts for an S type. In the end he had to go to a specialist in South London. Can't remember the name but I found it by Googling 'vintage Jaguar spares'
Simply searching for this line on Google > "s-type" "suspension bushes" > and then clicking on the 'Shopping' button seems to offer quite a few possibilities:
https://tinyurl.com/ya8x2ena
oh, they do them, but frequently get it so wrong, with different cars. Despite giving them my registration number and checking the correct model and variant, they have supplied me with incorrect oil filter and brake pads (Honda Accord), incorrect oil filter, air filter, rear wiper blade (Audi A4), incorrect wiper blades, headlamp bulbs (Audi A6)
With Douglas when it comes to Eurocarparts. I have used them for years and have an account for wipers and filters etc. They deliver the same day free of charge and are cheaper than Halfords by miles. Another point, if Halfords order a part for you.......they order it from Eurocarparts, and mark it up. Had wiper blades delivered this week by them and the service is exemplary. In the past I have purchased suspension coils, wheel bearings, light bulbs, hoses, brake discs, etc. etc. All quality parts that were fitted with no trouble.
No doubt bhg..... but comparing price and actual quality is not always the same. A pair of Aero single mould wipers, same make Bosch, were just under £7 cheaper at Euro and available, and delivered free of charge within 3 hours. Remarkable.
Togo - quite right but I've returned Bosch wiper blades because of poor quality and my last two Bosch batteries have only lasted 3 years each (one replaced under warranty). I'm starting to be edgy about Bosch quality.
Like me then bhg you spend a few moments shopping around, but reserve judgement until satisfied. As I said earlier, I am very happy to make use of the Eurocarparts site. When I was determined to keep my Mondeo Diesel 2.2 Duratorq STI GTI on the road without paying through the nose they were excellent. Sadly it is gone now, I have missed the "grunt" every time I drive since. But needs must, after all.
You could try ebay.
A few years ago the wishbone bushes failed on my Jeep (MOT failure), Fiat/Chrysler wanted over £900 for a new wishbone (not selling the bushes separately).
I found a man in Taiwan selling a pair for around £35 including p&p.