Just a thought Pete, but have you tried your local scrapyard?
Reason I ask is that I have a Toyota Rav4 Mk1 that's fitted with a scissor type jack, and it's a far better construction than the flimsy Renault 4 one.
Thanks for the suggestion - I've got a scissor type jack that is fine for the job but won't fit under the bonnet. That's why I was after a Renault one.
I would be very happy to have a jack. Would you be able to post it? If you could, please let me know how much you would want for the jack and postage and I'll pm you with my details.