Train leasing company Porterbrook have announced that some class 319 dual-voltage EMUs are to be converted into bi-mode trains for use on Northern.

It’s an interestng development. These trains were built for Thameslink in the late 1980s, operating on 25kV AC overhead along the Midland main line to Bedford, and on 750V DC third rail on the Southern Region, switching between the two at Farringdon.

It’s that dual-voltage capability that makes them suitable for conversion, since there’s already a DC power bus running the length of the train carrying traction current from the 3rd rail shoes on the driving trailers to the motor coach in the middle. The plan is to add underfloor diesel generator sets to the driving trailers, enabling the train to run on diesel power away from electrified routes while retaining AC overhead capability while running under the wires.

Rebuilding thirty-year old trains in this manner seems a bit “make do and mend” compared with shiny new trains. But it does say something about the build quality of rolling stock from the later years of British Rail that such a thing is being considered.

The famous viaduct at Knaresborough in North Yorkshire, built in 1851 to carry the line from York to Harrogate. At first glance you might think the train is a pair of class 153s, but it’s not. It’s one of the seven class 155s originally sponsored by West Yorkshire PTE, which were never split and converted into single-car units.

Although it now carries only local traffic, Knaresborough sees a surprising variety of trains; in the space of a few hours I saw class 142 and 143 Pacers, and class 150, 153 and 155 Sprinters.