Thanks lads.
I was lucky. It didn't fare too badly bouncing down 3 stone steps. Needed to replace the bent metal idlers (good thing the vendor sent me an extra pair by mistake. Ah - some things are meant to happen!).
I took the tank out into the garden and switched it on then went back into the shed to fetch the transmitter. Being a 2.4 Ghz system I didn't think it would get any spurious signals, but I was wrong. I was just reaching for the transmitter when I heard the tank start up. I rushed out the shed just in time to see the tank running gleefully at full speed for the stone steps. By the time I switched on the transmitter and tried to wrestle control back it was over the edge and bouncing merrily down the steps, shedding idler wheels, track and its turret as it went!
I wish someone was there to video it - the thought of £250 from 'You've been framed' would have gone a long way towards ameliorating my feelings at that moment.
Needless to say I gained full control of the beast as it was lying upside down on the stone path - I remember my language was somewhat choice at the time!
Lesson learned now though!
Cheers
Chris