Tried that already Andrea, and its set to allow cookies from sites I visit. But every time I close down the tab on which I've got mudcat open, when I come back it wants me to sign in. It doesn't happen if I leave the tab on, but start another and visit other sites. i tried clearing all my history etc, but that didn't. Help either.

It's pretty clearly a problem with Safari though - when I try using another browser on my ipad tge problem doesn't arise. That would be one way to solve it, stop using Safari - but it's the most convenient browser for me, I'd be reluctant to lose it.