Rather a long time ago I enquired as to why we had to do the compass swing questions for the ATPL and was told that the CAA, (actually BoT then!), had to assume worst case scenario. This might mean you have landed somewhere after a lightening strike, for example, and with no AME available, because you are multi faceted and can do compass swings you could over see a swing and legally depart! (Can you believe it!
).
Personally I forgot everything I knew about compass swings five minutes after the exams! If you really want to test yourself try the question that only gives three headings! I had to sit Instruments twice because of that, barstewards!
Lt. Kije, if you are still with us, invest in a 'phone call to the CAA in the UK. In the past they have sent out a form on which you list ALL your experience, licences held etc. return this form accompanied by certified true copies of your log-books and licences and a fat cheque, they then assess you and advise exactly what you will need to do to get a UK licence. As has already been mentioned, it is quite a lot.