(04 Nov 2015, 5:55 pm)DaveyBowyer wrote Initially, 5331 to 5338 were going to go on the X21 but, because of the major reliability issues on the X7 at the time given how premature the service was back then and the fact that single deckers would not match the needs of capacity on the X21, it was then decided not to put them on the Pronto.
Wasn't it also rumoured that the X21 would be increased to 20 minute operation when the rumour of 5331-5338 going on the X21 was around?