And is flight under IFR counted from chock to chock, as I am sure some bright spark in Policy will argue that you can't be flying under any rules until you are airborne!
The CAA cleared up their stance on this back in 2010 with this training com
FCL: Aeroplane: 2/2010: Trainingcom (Aeroplane) | Publications | About the CAA
They quite clearly state that taxi time cannot be counted and instrument flight time.