Goldcrest of Firecrest?

Thanks for the tip Alan.  I've just up a 'curtain' over the shed window.  They are very speedy so yes I will need some luck to get a decent photo :)

Good luck in getting a photo Lesley you might want to consider covering up the shed window, the bird is attacking its own reflection thinking it's a rival, they can hurt themselves.

One keeps flirting with his /her own reflection in the shed window!  I'll try and get a photo.....

Thanks Alan. -  I'm now sure they are firecrest.  They are the most gorgeous little creatures.  They are very busy in the conifers -not sure if they are nesting?  Been around for about 4 days - seem to be getting on well with my family of blue tits but the blackbirds is another story - seems to be lot of chasing by the blackbirds going one!