I think this will explain it:
A Boeing 747-200 which served with British Airways until 2002 as City of Birmingham, G-BDXJ, was purchased by Aces High Limited, a company specialising in supplying aircraft for television and film work, and transferred to Dunsfold.
It was modified and used for filming for the 2006 James Bond film Casino Royale. Some of the scenes set at Miami International Airport were filmed at Dunsfold. It has also appeared in the background of numerous Top Gear episodes and directly in an episode where it is towed by a JCB Fastrac tractor. It was also towed by a Volkswagen Touareg in a 2006 Fifth Gear episode, the same year that the modified aircraft and Dunsfold Airfield were featured in a television advertisement filmed for the Volkswagen Touareg, demonstrating the vehicle's towing ability. In 2008 it featured in a episode of Scrapheap Challenge in which contestants created machines to tow the aircraft.[citation needed] Modifications to the aircraft include the removal of the existing Rolls Royce engines and replacement with twin mount engines, similar to those fitted to aircraft such as the B-52 Heavy Bomber.
Courtesy Wikipedia
