http://mercurio.iet.unipi.it/pix/gb/ele ... WT4VEP.jpg (for people who dont know what a 421 is
The least reliable is Wales and Borders class 143 (pacer). Although over the last four weeks the least reliable train has been MMLs HST sets!
Reliability is based of miles per casulty source: Modern Railways: January 2004. A good buy