Thank you for your reply.
However, as asked, what course of action should he take before contacting HMRC?
Also how should he contact them? - by telephone, if so what telephone number should he use, or in person at a local branch of a HMRC office
What is he allowed to include in the calculation of net income, apart from rental payments, and does tax payable have to take into account personal income tax threshholds applicable during the 15 year period, i.e. is it taxable at 20% and/or 40%