Re.Max Chat's information: the tax allowance is based on
commercial standing not just professional status. Some Police pilots, even though working for commercial companies, have needed BALPA intervention to get their allowance (because the tax man said police flying was public service and not commercial flying)
However one or two directly employed police pilots have recently managed to get the allowance, so I guess its up to the interpretation of individual tax offices.
To save TC a simple google search;
http://www.hmrc.gov.uk/manuals/eimanual/EIM50050.htm