It seems to be a bit unfair highlighting the TSA and the US over this. The pat down search only applies if you refuse a body image scan -in the UK you have apparently have no right to refuse the scan - and may still be physically searched afterwards.
From the Manchester Airport Web site
Following trials of “imaging technology” (also known as security scanners) in
Terminal 2, Manchester Airport has now extended this enhanced security measure to
Terminal 1 & Terminal 3.
Please note: From the 1st February 2010, additional Government legislation came into operation at this airport, which states that any passenger who refuses to use the scanner will be denied travel.
Link Here
Manchester Airport : Security Scanners Public Information