Chula ambulance

Chula ambulances were vehicles used by the Chula to heal their warriors on the battlefield. They were filled with nanogenes and, like all Chula vehicles, could travel in time.

History
Jack Harkness stole an ambulance and a Chula warship. He used the ambulance to lure the TARDIS, which he thought contained Time Agents, and landed it in London 1941. He wanted to con the "time agents" into thinking it was a Chula warship, and made sure a German bomb was to land on it, obliterating it. Little did Jack realise that if this happened, the nanogenes would escape and cause the Empty Child plague.

The ambulance was guarded by the British Army. The Ninth Doctor destroyed the ambulance so it couldn't cause any more trouble. (TV: The Empty Child/The Doctor Dances)