After fifty years of service the lives of the HST 125s are now drawing to a close. Some remain to remind us of the extraordinary impact these trains had on British Rail's operations over so many decades, but their number is dwindling fast. A long goodbye, but a goodbye nonetheless. With their days numbered, now would seem to be the time to consider the achievement of the design engineers who created them and the service they rendered across Britain's rail network, aided by so many others.It is a story that might never have been told if BR's plans for its Advanced Passenger Train had reached fruition more quickly. But delay upon delay meant that there was pressing need for a fast modern passenger less technically advanced substitute to fill the gap. The 125s were the result and very quickly they showed what they could do, and would continue to do wherever BR, or the privatised companies that followed in the 1990s, operated them.This book pays homage to these exceptional trains and all those who were involved in their design, construction and day to day operation.