Ailanthus altissima ('Tree of Heaven', aka., 'Tree of Hell').

Common weed tree in much of the USA introduced from China.--Highly invasive here and out-competes native vegetation.

The thing that nailed the identification is that peanut smell!

(You will find no love for it here.)

jumarkid - you'll find them growing in the UK too. It's beginning to be a bit invasive in the warmer micro climates of the SE, especially London. I have seen a few seedlings here in Somerset in very sheltered town environments. But it is much better behaved here than in the US.

Here is a link that might be useful: Ailanthus altissima

Thanks to all responders, I know tree of heaven in uk, similar to ash but the timber very dense and heavy. What threw me here was the tree had been coppiced and the new growth very vigorous, also I had never noticed that strong peanut smell of the leaves, maybe the Mediterranean climate here increases the smell.