Flesh? Flies Mating

I have never got to grips with identification of True Flies - I think I would need a book as good as 'Britain's Hoverflies' to even try. However these flies mating attracted my attention so I took a photo and then tried to see whether they could be identified. As far as I can tell they look like Flesh Flies but that's as far as I can go - and I'm not even sure about that.