I have a 2005 RRS 2.7 TDV6 with 60k. We have had electrical problems over the last 12 months (alternator has been checked, ECU has been dried out as was completely waterlogged).

Today had a 'new' one - when hitting a bump in the road the whole vehicle shut down - electrics/steering/engine. On stopping and restarting all seems fine again - until the next pot hole!

Has anyone had anything similar?

Sounds like the vehicle thinks it's crashing. I'd have thought that a loose connection wouldn't reset without physical intervention. 2012 SDV6 - it's missing a couple of cylinders
2008 TDV8 - it was a labour of love and is much missed

check the battery terminals, i had this on a car i owned many years ago

Sometimes my radio goes off for a second when I hit bumps,
that's annoying.Wouldn't know where to start trying to find out why. 

Supporting the London Air Ambulance with my Brothers

I agree with Monty- I had the very same thing and one of my terminals was loose. Especially if fiddling about with the battery has happened.

Hello Alex. did you manage to source the cause of your engine failure. same thing happened to me 5 times this weekend
each occasion I was travelling at 70 hit bump on the carriageway and dash went out, lost engine and had to cruise to a standstill luckily each time we were on a relatively straight road. Started after each time, only thing that came on was parking brake light (something I never use due to previous issues). any insight would be greatly appreciated.

If ECU was waterlogged - chances are there are other electrical issues caused by this sort of damage. Could be loose or corroded connection that shorts out when jolted anywhere in your system. I'd certainly start with battery and battery cables as well as ground straps (chassis) and alternator connections. Look for loose or corroded wires. But this may be hard to find and need I indie with electrical expertise to start measuring resistance on your wiring loom etc.

Good luck

Thanks, battery checked ok, will work backwards from there. LR guy seems to think it is something behind the dashboard.
Will post result as soon as poss.