Long-winged Conehead (Conocephalus discolor)
Whilst similar in size there are two main distinguiching features between the two. The first is, obviously, the wings which on this specimen go right back to the tail end. The Long-winged does not have such a dark brown stripe down its back either.
Long-winged Coneheads are quite common across southern England now but not always easy to find as they like long grass and scrub in which they can hide and from where they make their continuous and fairly loud stridulating sound (a bit like a distant knife grinder says my book!) so I was most fortunate to find this one out in the open.