The fast, frequent service resulting from the introduction of the first generation of electric trains in 1931 was a significant contributor to suburban development in the Stretford, Sale and Altrincham districts, south-west of Manchester.

Even in the early days, it was clear that the dead-end terminal at London Road would need to be connected to the other railway lines serving Manchester.

Frequent disagreements between the two owners resulted in the appointment of a full-time independent arbiter to resolve disputes and ensure the day-to-day functioning of the railway.

In the early part of the 20th century, the MSJ&AR steam trains came under increasing competition from electric tramways, which by that time ran the whole way from Manchester to Altrincham and closely followed the route of the railway.

The LNER was particularly interested in the electrification of mainline railways and in 1928 a government report had recommended 1500 V DC overhead as the national standard system.

The new rolling stock was of wooden frame construction and a conservative design, with individual compartments throughout (without corridors) and offering both first- and third-class accommodation.

The Altrincham Electrics provided a faster, more frequent service than the steam trains they had replaced, and resulted in an 89% increase in patronage on the line within the first five years.

The new electric service also stimulated further suburban housing development close to the line, and provided an early example of today's marketing taglines when the railway's publicists dubbed the initials MSJ&AR as Many Short Journeys and Absolute Reliability.

As well as local trains, the Altrincham Electrics also provided express services at certain times of day, making use of a four-track section of line between Sale and Old Trafford.

These projects were disrupted and delayed by World War II, but in 1954 the first mainline electric railway in northern Britain was completed from Sheffield Victoria to Manchester London Road via the Woodhead route, using 1500 V DC overhead.

In common with most railway routes, passenger traffic on the MSJ&AR declined significantly in the 1960s as travel patterns changed and more people had access to private cars.

In the 1950s, British Railways chose 25 kV 50 Hz AC overhead in place of 1500 V DC as the standard for all future main line electrification outside the Southern Region.

Rather than replace them with new rolling stock operating on the non-standard 1500 V DC system, the decision was made to withdraw the trains and convert the whole Altrincham line to 25 kV AC.

The unique 40-year-old, three-car Altrincham Electrics were replaced by 12-year-old, four-car Class 304 25 kV AC EMUs, based at Longsight depot.

In the event, the line was closed for some six months, during which time both all-stations and a rush-hour express (first stop Sale) substitute bus services were provided.

Rail tickets were valid on the replacement buses, operated by the North Western Road Car Company and running daily except Sundays.

By contrast, peak-hour demand proved lower than originally forecast due to fare increases over those previously in force for British Rail services.