Taper trouble

My client is an individual who owned some industrial units which she acquired prior to April 1998. Each industrial unit was let to an unquoted company unconnected to her which traded from the unit.

On disposal of the units in the year ended 5 April 2008 taper relief was claimed at the non-business rate for the period 6 April 1998 to 5 April 2000 and at the business rate for the period after 5 April 2000.

HMRC disputed the claim for the latter period saying that 'assets used as lettings were not considered to be business assets until 6 April 2004' referring me to the Capital Gains Manual at CG17937. I checked CG17948 and the then wording of TCGA 1992 Sch A1 paras 5 and 6 and felt this appeared to say that business taper did apply from 6 April 2000 and wrote back...