I seem to recall that when NG first entered the market, they intended to produce all of the world tail 757s (I could be mistaken). In the end, they (have) only made 4 - Blue Poole, Chelsea Rose, Benyhone Tartan and Grand Union. Around this time, Gemini also released Animals and Trees.
The latest release was the NG Chelsea Rose 777-200ER a couple of years ago.
Many years ago I built a spreadsheet of all the BA world tails and which designs had been released. From my count, there were 188 different combinations of designs / aircraft of which only 66 have been released (ignoring variations of the same scheme).
There seems to be a number of "big" omissions from the list of released aircraft (please correct me if I'm mistaken):
747-400:
- Chelsea Rose in standard livery (G-BNLA, BNLL, BYGA, BYGC and BYGF). Gemini and Big Bird released the British Asia Airways titles (G-CIVB) and BA World Cargo (N495MC) only.
- Benyhone Tartan with British Asia Airways titles (G-CIVA)
- Special mention to Delftblue Daybreak. Gemini released G-CIVN but as far as I can tell, the tail design is incorrect (since different aircraft sometimes took different parts of the base artwork). It looks like Gemini copied the design off a 777 (G-RAES) without realising the design on the 747 was different. This scheme was worn by four different aircraft (G-BNLD, CIVC, CIVN and CIVT).
777-200ER:
- Delftblue Daybreak (G-RAES, VIIU)
- Waves and Cranes (G-VIIM) - although this appears there was a Gemini sample which indicates it was planned for release.
- Colum (G-VIIP)
767-300ER:
- Chelsea Rose (G-BNWB, BNWE, BNWR)
- Ndebele Emmly (G-BNWD)
- Colum (G-BNWK, BNWV)
- Blomsterang (G-BNWU)
- Waves and Cranes (G-BZHC)
There are huge gaps in the A320s (only 1 - Wings - was ever released), 737-400 (only the Gemini twinpack of Crossing Borders and Blue Poole was released) and 757-200 (being only the aforementioned NG and Gemini releases).