Kerria japonica

Might have come through from under the fence? Has pretty yellow flowers but is a thug.

that's certainly what it looks like - I bet next door's got it on the other side of the fence and that's where its coming from.

Not a Kerria. The picture shows opposite, compound leaves, while Kerria has alternate, simple leaves. It actually looks more like a Campsis vine than a shrub, to me.

I think you're right, Tugbrethil - I thought campsis when I first looked at it, but then went for Kerria.