In the following video Ross Noble tells an interviewer that you can drive a tank on UK roads and also that it is congestion fee exempt. If we ignore for a moment the practical issue of driving a tank through London is this actually true, is it really exempt?
It depends on the size and age of the tank.
If the tank is over 25 years old, it won’t need an MOT. Road tax is a contentious issue: some claim that tanks are road tax exempt, but the DVLA claims that it depends on the size, weight and intended usage of the vehicle. To drive a tank on the road without a learner plate, you’ll need to pass the category ‘H’ license examination. To register the tank, go to your local DVLA office. You’ll need a V55/4 form if the tank is new, and a V455/5 if it is second hand. source
More info about using a tank on road: https://www.intotheblue.co.uk/blog/2015/04/17/the-essential-guide-to-where-to-drive-a-tank-and-who-can-drive-one/
Edit: The main text says about congestion fee, but don't inform the sources.
Checking regulations I found no information about this clain:
You don't have to pay the Congestion Charge or register with us if the vehicle is recorded at the DVLA or DVANI in one of these categories:
- Two-wheeled motorbikes (and sidecars) and mopeds Emergency service vehicles, such as ambulances and fire engines, which have a taxation class of 'ambulance' or 'fire engine' on the date of travel
- NHS vehicles that are exempt from vehicle tax
- Vehicles used by disabled people that are exempt from vehicle tax and have a 'disabled'taxation class
- Vehicles for more than one disabled person (for example Dial-a-Ride) that are exempt from vehicle tax and have a 'disabled' taxation class
Taxi and private hire vehicles (PHVs)
Taxis and PHVs are exempt from paying the Congestion Charge when actively licensed with London Taxi and Private Hire (TPH). The exemption for PHVs only applies to private hire bookings
Certain vehicles, including buses, registered in European Economic Area member states, must also be registered with us to qualify for an exemption
- HM Coastguard and Port Authorities
- Certain operational vehicles used by the London boroughs
- The armed forces
- Royal Parks Agency
- Breakdown organisations source
Yes, tanks are exempt from the London congestion charge. As are armed forces vehicles generally. As long as they're actually being used by the armed forces.
Other categories of exemption include: ... The armed forces
Tanks are generally only driven through London by the armed forces, so it's a reasonable claim.