Avro 687 XX( Twenty)
Just as the Lancaster was developed into the York, a similar passenger airliner was planned from the Lincoln. The Avro XX designation was a reversion to Avro's prewar transport naming, following on from the civil Anson (Avro XIX). Initially constrained by the wartime necessity of using the maximum commonality with the Lincoln, the Avro XX was very much a compromise aircraft, and in the end was decided to be just too much of a compromise to be viable.
Avro 688 Tudor 1
As the war drew to a close Avro was able to take the Avro XX design and rework it to be an actual airliner rather than a modified bomber. The wing was moved from being shoulder mounted to having the spar run under the floor to give an unimpeded cabin.
However the Tudor was aerodynamically unsuitable, and flight testing required modifications to the rudder, tailplanes, wing root fillets and the rear of the engine nacelles. Internally problems with the heaters and pressurization were never fully rectified.
The Tudor 1 also suffered from Avro's design being a winner for a pre-war market, but an anachronism in the post-war world, and with BOAC finally losing interest in the aircraft the design was doomed. Plans to manufacture the aircraft in Australia were dropped, and the Tudor 1. Most of the aircraft were eventually converted into Tudor 4's.
The Tudor 1 prototype has the distinction of being possibly the only large aircraft to have ever flown without a lick of paintwork. The initial test flight was flown without any registration or any other marks on the aircraft.
Avro 688 Tudor 4
In an attempt to make the Tudor 1 more commercially viable, the aircraft were given a fuselage extension to become the Tudor 4. However the Tudor 1's internal problems still plagued the Tudor 4, and 2 unexplained aircraft losses led to the aircraft being banned from passenger service, leading to the Tudor 4's beinge relegated to become freighters.
Finally with the Tudor 4B Super Trader the aircraft's original promise was realised as all the aerodynamic and systems problems were resolved by Aviation Traders (Freddie Laker's company that eventually produced the Carvair), however by that time the Tudor was thoroughly outdated.
As a further development of the short-body Tudor, the Avro 711 revised the Tudor 4 to become a nosewheel aircraft, with the new broad chord fin and the engines upgraded to the RR Griffons of the Shackleton. The design however was never realised.