I do sympathise with the above posters, mainly because my Air Force parents went through the same thought processes years ago when stationed abroad. Their ex pat friends enjoyed an enviable lifestyle (tax-free, of course), whilst the poor old Services folk enjoyed their tax deducted at source.The Inland Revenue web site is quite informative at
www.inlandrevenue.gov.uk
and this page mentions Crown Servants
http://www.inlandrevenue.gov.uk/cnr/faq2.htm