The Meteor was Britain’s first operational jet fighter, and is a contemporary of the ME 262 and P-80 Shooting Star from the late WWII era. Martin-Baker has been using this pair of modified Meteors to test ejector seats for decades.
The main modification is the open aft cockpit- that is the test compartment the seat blows out from. Apparently, there are a few reasons for using the Meteor.
One is simplicity – the Meteor has very basic electronics, and they are very simple to maintain. The other reason is less straightforward.
Ejector seat tests are often done at low altitude, between 25 and 400 feet. At these heights, bird strikes are a big risk.
The Meteor is twin-engined and can be flown safely on just one if an issue does occur. The engines themselves are antiquated centrifugal flow designs, and as such, the compressor fans are not exposed from the front. Though less efficient than an axial flow design, they’re totally immune to bird strikes!