The Mason Wasps, genus Ancistrocerus, are all very similar. The basic color is black, covered with yellow lines and other yellow markings. There are at least 12 Ancistrocerus species in Britain and they are very difficult to identify, but this one appears to be A. parietum, one of the two most common to the UK.
The females look for a good place to build a nest. That may be a hole in a tree used by a beetle but man made holes in wood are also accepted happily. The wider the hole the bigger the cells in the nest are. In the past Mason Wasps were considered to be closely related to the Potter Wasps and they are still often referred to as such.
This is as far as I know, that I have ever seen one for certain, let alone photographed one (even if it is not the best due to hand held camera shake!).
Camera Maker: Canon
Camera Model: Canon EOS 70D
Lens: EF100mm f/2.8 Macro USM
Image Date: 2014-07-23 11:29:17 +0000
Focal Length: 100mm
Exposure Time: 0.011 s (1/90)
ISO equiv: 800
Exposure Bias: none
Metering Mode: Matrix
Exposure: aperture priority (semi-auto)
White Balance: Auto
Flash Fired: No (enforced)
Color Space: sRGB
GPS Coordinate: undefined, undefined
Creator: Paul Iddon
Copyright: Paul Iddon - A View of the UK