Saffron Walden Crank Up

[Pride of Somerset]

I have always felt that like many Garrett 4CDs it originally had a 'BJ' registration - painted on.... A later interpretation, perhaps from a rusted plate was 'EJ' - which as you say, Trystan, is Cardiganshire. I don't think there is a record of it in Cards registration.
A similar instance in my opinion is the Burrell Scenic, Perseverance the Second, whose registration is WR9110, but for a few years in the fifties ran as 'WB'.