This is a new bug to me. I saw one in April (but only got a blurry photo) and then found another earlier this week. Meet the Cinnamon bug (Corizus hyoscyami), also known as the Black and red squash bug. Though bugs can be difficult to identify, this one has very distinctive markings so is easier than most. In times past, the Cinnamon bug was only found along the southern coasts of England but it is now spreading north, and west into Wales, obviously. You can read more about this colourful mini-beast on the British bugs website.