Class 37 Locomotives were introduced to British Rail from 1960 onwards and eventually numbered 309.In Scotland, they were initially allocated to Eastfield and Polmadie depots in Glasgow and Haymarket Depot in Edinburgh.They became known as Type 3s and were used for both passenger and freight services.In later years, during the privatisation era, the Class 37 fleet became dedicated to various coal workings in the Ayrshire and Lothian areas.A number of the class were also upgraded at Crewe Works in the mid-1980s with electric train heating (ETH) for the West Highland and North Highland routes. This book covers the class from the mid-1970s in the BR era, through sectorisation and on to privatisation and beyond.The locos performed reliably and worked all over Scotland.Some are now preserved at various heritage lines throughout the United Kingdom.