Probably either Leafcutter bees or, worse, vine weevil , info on vine weevil in the link below

http://www.defenders.co.uk/pest-problems/vine-weevil.html

looking at the shape of the holes I'd go for leaf cutter bees.

welcome to GoY too :o)

Thanks for your responses, Sue99

I agree. If you stand about long enough you might see a bee inaction - the cut round the bit they want and fly off with it. Only seen it done once.