“Come hither, hither, pretty Fly, with the pearl and silver wing;
Your robes are green and purple — there’s a crest upon your head;
Your eyes are like the diamond bright, but mine are dull as lead!”
~ from ‘The Spider and the Fly’, a poem by Mary Howitt, 1828

I’m not sure what the fly is (probably one of the Calliphora species) but its stalker is a Zebra spider (Salticus scenicus), a very common jumping spider that can be found, as this one was at Sully last week, sneaking up on its prey on sunny rocks and walls.
And what do you think happened next?