Chiltern Railways is preparing to wave goodbye to its affectionately named “bubble cars” as they make their last journey next month.

First brought into service in Britain in 1960, the two heritage class 121 trains were purchased by Chiltern Railways in 2003 and have serviced the 18-minute journey from Princes Risborough to Monks Risborough, Little Kimble and Aylesbury ever since.

The bubble cars were recognisable for their small size and open environment that allowed customers to see ahead through the front windows of the train.

Famed for being the last remaining trains in service that use vacuum brakes, Chiltern Railways say the time has come where the ongoing maintenance of the trains is increasing and the decision has been to take them out of service.

Both trains will be on sale following their retirement on May 19 and the number of services running daily across the route will remain unchanged.

Matthew Prosser, Engineering Director at Chiltern Railways said: “We will be sad to see these trains go has they are a part of railway history and some customers even make special journeys to travel on them.

“However, the changes are necessary due to the age of the vehicles and we will ultimately be providing a more comfortable service for our customers.”

A small farewell will be held on the last day of the service for the bubble cars, with details set to be announced soon.