Thank you Pholi. I went to target before and got a couple of pairs of "seam free full briefs", which claim to "flatten the tummy". We shall see. I bought them in my usual knicker size, and I'm currently wondering how I am going to get myself into them. Perhaps with a shoe horn.

If I was any good at sewing, or had a machine, I would probably have a go at sewing up some of the ribbing fabric myself, just as you have done.

I might also see about finding the tubigrip again. Thanks for the advice!