Thanks, Clare. Actually I was in the garage yesterday and remembered I had some old-fashioned metal bakers' trays left by a previous owner - the very heavy, mesh kind. I embedded these over the plants and covered them with earth and mulch. Looking this morning, it seems to have done the trick - the animal has been scrabbling around but hasn't managed to dig up the plants.

It has polished off the dishes of fat cake and fruit left out for the birds, though (or at least, I'm assuming it's the same animal). I'm sure it's too powerful for a squirrel, though - I'm still intrigued to know what it is!

Many thanks,

A.