Big airlines, such as Lufthansa and KLM, have had a happier time than niche rivals with all-business-class routes – and BA is set to join the fray next year.

Most of the carriers are using Boeing and Airbus aircraft operated by PrivatAir, a leading Swiss business aviation group. The aircraft are equipped with about 48 seats, which convert into fully flat beds, rather than the normal configuration of about 150 seats.