Shopping relief

I have an ongoing case with HMRC regarding my client Mr E who purchased a shop on
19 December 2003 as an investment. Following some conversion work this was let on 2 January 2004. My client had many problems with the tenant who he subsequently evicted on 24 July 2004. The premises were sold on 11 April 2005 without any further tenants taking occupation.

In my capital gains computation I have claimed one year's business asset taper relief as in my opinion this was a business asset throughout. HMRC are saying that business asset taper relief is only available whilst a trade was actually being carried out at the premises.

The legislation and HMRC manuals seem silent on this matter.

Does anyone have any advice as to the amount if any of such relief that the client might be entitled...