I think if it if it fully lined the lining is the problem.
we have a large rug on a carpet and I bought an antislip liner thingy from John Lewis, it was about £60 and worth every penny .You cut it to size and it goes under the whole rug. I agree though that it may be your carpet that is the problem.
Good luck especially if you love both carpet and rug.
What were the first ever records that you bought and when?
To think that London, or anywhere else for that matter, does not belong to any one demographic