The hornet (Vespa crabro) is a big cousin of the wasp, and has become more common in the UK possibly due to global warming. This is my first photograph taken Toft though have sighted it before. Definitely a new invader that is spreading north very quickly is the Ivy Bee (Colletes hederae).This bee was first recorded in the UK in 2001, it has now been found in much of southern England and Wales and in the Channel Islands.
There is a mapping project for this - http://www.bwars.com/content/colletes-hederae-mapping-project.