In Slutspel I Kalahari, Biggles and Bebe Sunday used what appears to be a converted Douglas A-26 Invader as an executive transport to support a hunting safari in the Kalahari desert.
Bebe Sunday lands in what looks like a A-26 Invader which Biggles is using as an executive transport. The illustrations in the comic strip are all very small but note the notch at the rear where the plexiglass of the rear gunner's position used to be.
This is quite an interesting choice of aircraft. The Douglas A-26 Invader was an American World War 2 twin engine light bomber and ground attack aircraft. It also served in the ground attack role during the Korean War and, because of its relatively high performance and heavy armament, examples of the Invader continued to serve right up to the Vietnam War. The last military Invader, in the Colombian Air Force, did not retire until 1980.
The Invader is a plausible choice as an executive transport in the immediate postwar era in which Slutspel is set. There were certainly significant numbers of postwar civilian conversions, such as the On Mark Marksmen which even featured a pressurized cabin. Indeed, the Invader had a performance which would make it a candidate for the real aircraft behind the Parkington Pacemaker which featured in Biggles Hunts Big Game, although most artists who have illustrated the story chose to draw an equally plausible conversion of the Lockheed Ventura or PV-2 Harpoon.