The Advanced Passenger Train (APT) programme is remembered by many as one of British Rail's greatest embarrassments, an ambitious but ultimately unsuccessful design. The APT-P multiple units incorporated ideas that were well ahead of their time, most famously including a computerised tilting system which allowed the trains to navigate the tight turns of Britain's ageing railways up to 40% faster than anything else of the time.

The first APT-P unit was introduced in 1979 and the trains were progressively developed until 1987, the highlight being a period of passenger service between 1983 and 1985. Ultimately the complexity and cost of the unreliable APT saw it replaced by the simpler and considerably cheaper IC125 HST programme, but lessons learned were incorporated into the IC225 programme and later the tilting Alstom Pendolino trains still operating on the West Coast Mainline.