NB. I've been doing a little research on this striking Cricket, and it seems that before 1980, it was regarded as relatively rare. A report from Buckinghamshire in 2006 (only that recent) was certainly noted as being out of the ordinary, although becoming a trend, so I may have been a tad premature when I suggested they may have got as far as Liverpool! I KNOW they are in Worcestershire though.
I'm also led to believe their "song" is similar to that of a "Savi's Warbler" - in case that helps you at all!
There is an article in the September 2001 issue of New Scientist magazine suggesting that the incidence of long-winged Roesel's Bush Cricket has risen from a few percent to a third of the entire population, as opposed to the short-winged variety, over twenty years.
This is attributed to global warming.
I should have guessed.