I think it's one of New Zealand's 70 something species of native weta which apparently made its entry overnight through a partly open window. I really would like to think its appearance is due to my "no spray" regime in the garden over the past three years and that this is evidence of my garden becoming home to an ever increasing amount of insect life. Alas, I fear that is not the truth of the matter (although I'm sure the insect population is increasing). I think this handsome visitor probably hitched a ride on a trailerload of firewood that my neighbour brought in from a forest in the country and parked in his driveway overnight. It has been released gently and lovingly amongst some rhododendrons. Perhaps it is bearing eggs and will populate the garden with its progeny!
For the record, the body is about one and a half centimetres (three quarters of an inch) long - a mere miniature compared with some of the giant species in the New Zealand bush.