The Parkington Pacemaker is a fictional aircraft type which appears in Biggles Hunts Big Game where it was the main aircraft type operated by Stellar Skyways, an airline operated by the international counterfeiting ring led by Kravas. The great distances involved in the plot implies that the aircraft must have exceptional performance in terms of range and speed. In one instance, Tug Carrington and Ivan flew a Pacemaker non-stop the 2000-odd miles from London to Cairo. The Pacemaker also flew regularly the non-stop trip of 1800 miles from Cairo to Kudinga and back again. No refuelling was ever mentioned and it seemed unlikely spare fuel would have been stocked in large quantities at Kudinga. This implies that the Pacemaker must have a range of at least 3600 miles.
In terms of speed, Ginger observed in the 5th chapter "Hunters' Tour" that the Pacemaker could do 300 miles per hour and hence complete the 1800 mile sector between Cairo and Kudinga in 6 hours.
The problem is hardly any civil aircraft in 1947 were capable of these performance numbers. Almost all passenger aircraft of that era averaged speeds of 200 miles per hour at best. In fact, the Learstar, a special modification of the Lockheed Lodestar, with vastly improved performance, was marketed as the fastest executive transport in the world with a speed of 321 m.p.h. but this only came out in 1953!
The best analogue for the Pacemaker would be that it was a civil modification of a high performance military type, many of which became surplus after the end of World War 2. As mentioned above, the Learstar was a high performance modification of the Lockheed Lodestar. The Oakland Centaurus (first flown 1958) was a modification of the Lockheed PV-2 Harpoon, seating 8 to 11 with a maximum speed of up to 328 m.p.h. and a cruise speed of 280 m.p.h. with a range of 2000 miles. So Parkington might have taken a Lockheed PV-2 Harpoon, sacrificing some of its seating for extra fuel tanks and leaving only 8 seats to produce a civil airliner with the required performance numbers.