In message , Ronald Raygun writes
It's either allowed or it isn't,
Now I have gone and done some research!!
IR150 is as vague as I was "186. Similarly, the interest on a loan or overdraft may not be allowable, or only part may be allowable, where the borrowing is, for example, used: ? to buy non-rental business investments (which may be shown in the balance sheet as assets); ? to buy private assets or assets for your family; ? for the provision of the private funds you take out from your rental business.
187. Deciding what interest, if any, can be deducted may be difficult, particularly where your account with the business is overdrawn. That is, where you have drawn out more money than the profits of the rental business. The loan may have, for example, partly financed the rental business and partly met your private living expenses. Interest on a borrowing which you use to fund your private living expenses or other non-business expenditure isn?t allowable. We suggest you consult your professional adviser or the tax office if you are in doubt about the interest you can deduct.