Roll Over relief on Property Letting

Client purchased a property in June 2000 and after refurbishment sold in Nov 2006. Intention was to rent out and buy more properties. Property was never rented out but sold to finance purchase of further property. Client assumed no Capital Gains due to roll over relief. . HMRC now calculating Capital Gain and dismissing rollover relief quoting TCGA92/S152. Question being asked is intention to trade sufficient for elligability for roll over relief or even is roll over relief available on rental properties.