Commonest by many hundreds to one was this above - Marmalade Hoverfly.
Above - This one is a bigger one, Pied Hoverfly.
Then its more tricky. Above is Eupeodes latifasciatus.
And its mate, Eupeodes luniger.
This is the first time I've really looked closely at these and I'm sure I'll be taking more notice in future. Click on them for a bigger image.