Bessie

Bessie was the Third Doctor's main mode of transport during his exile on Earth. It was also used by his Fourth, Seventh and Ninth incarnations.

Modifications
Bessie was a canary-yellow roadster. It was acquired by the Brigadier for the Third Doctor's use as part of the exiled Time Lord's agreement to assist UNIT in its efforts to protect Earth. The Doctor had requested a car of this nature after taking a liking to a similar vehicle during his first fight against the Autons (DW: Spearhead from Space).

The Doctor made several modifications to Bessie during his time at UNIT. These included an anti-theft force field (DW: The Ambassadors of Death), which magnetically trapped anyone attempting to steal Bessie; a remote control (DW: The Dæmons), with which the Doctor could steer the car from a distance; and a minimum inertia hyperdrive, which allowed him to drive at breakneck speed and still come to a sudden stop without him or his passengers being sent through the windscreen by inertia, which the brakes absorbed. The Doctor made use of this inertia absorption to overtake the Brigadier's Land Rover after Lethbridge-Stewart had declined to travel in Bessie due to fear about the car's reliability. (DW: The Time Monster)

Early use
When he began his exile on Earth, the Third Doctor (who had just regenerated and not fully recovered) stole an antique roadster parked in front of Ashbridge Cottage Hospital so that he could get around. He liked it and, while seeing to it that the car returned to its rightful owner, the Brigadier said he thought he could get something like it. (DW: Spearhead from Space)

Bessie proved instrumental in capturing the Master. When he attempted to steal the Doctor's car and make good his escape following the events at Devil's End, the Doctor used his remote control to steer the Master back to the waiting UNIT soldiers, who took him into custody. (DW: The Dæmons) Bessie was briefly pulled into Omega's universe during his attempt to capture the Doctor. (DW: The Three Doctors)

Shortly after his companion Jo Grant left him and the third incarnation of the Doctor had temporarily left Earth, his fifth incarnation arrived on Earth and borrowed Bessie while helping UNIT defeat the Xaranthi (PDA: Deep Blue)

The car was also abducted along with the Doctor into the Death Zone, where it was heavily damaged by one of the thunderbolts that periodically rained down upon the landscape. (DW: The Five Doctors)


 * Presumably it was Rassilon who returned the car to Earth at the conclusion of this adventure.

With his waning lack of interest in affairs at UNIT and Earth, the newly-regenerated Doctor only drove Bessie during his first adventure (DW: Robot). At some point after this, Brigadier Lethbridge-Stewart had it "put into mothballs".

It was brought out briefly in 1997 as the Brigadier and UNIT worked together with the Doctor's seventh incarnation to battle Morgaine. (DW: Battlefield).

The Ninth Doctor may have used Bessie at some point, as R Spendsmith posted in the "Who is Doctor Who?"guest booklet:


 * "I don't know if he's the same bloke but he's the spitting image of a bloke I saw broken down at the side of the road the other day. He was driving some old yellow vintage thing and the man was looking well confused."

Registration
Initially, Bessie carried the registration license plate "WHO 1". Whether this was intentional - possibly chosen by the Doctor as a reference to the question often asked of his name - or a coincidence is not known. By seeming coincidence, at the time of the Seventh Doctor's encounter with Morgaine, the plate had been changed to WHO 7. (DW: Battlefield) When the Eighth Doctor utilised Bessie during the 1997 invasion of Britain, a UNIT soldier reported the number plate as "Whiskey, Hotel, Oscar 8," that is, "WHO 8". (NA: The Dying Days)

Behind the scenes

 * The actual registration WHO 1 was already in use in real life by another motorist, so Bessie was actually registered under a different number plate, MTR 5. Special WHO 1 number plates were made, which were used on the car when filming on private ground or on the public highway with permission from the police.
 * A photograph of Jon Pertwee driving Bessie appears in the frame of a mirror owned by Pertwee's character in the 1971 film The House That Dripped Blood. At the time of filming, Pertwee was still playing the Doctor.
 * Phil Collinson said he paid 50p for a ride on Bessie round a shopping centre when he was a child.
 * Model car manufacturer Corgi made a Bessie in a series of models built to commemorate an anniversary of Doctor Who.