How many times have we heard the phrase 'they don't make them like they used to'? Whatever the merits or otherwise of applying such a comment to UK railway locomotives, the fact remains that there are many longstanding survivors from our railway past. Of course, we all know of the role played by preserved railways in the UK; they have secured a place in history for heritage diesel and electric locos as well as many steam examples. But a number of ageing locomotive classes still remain on rail operators' books. Many are over half a century old. A quick tally suggests at least fourteen classes and, more importantly, between 100 and 200 individual examples remain on the network. They continue to attract more than their fair share of interest, particularly among the nostalgia enthusiast market. Yes, some are sidelined but many still see day-to-day service in the hands of mainstream operators. These locos are '50 not out', and the level of variety is perhaps surprising. This book celebrates some of those that have passed their half century and continue to work passenger or freight services.