Dissatisfied with the reliability of its AEC Merlin and Swift single-deck buses, London Transport in 1973 purchased six Leyland Nationals for evaluation. Liking what it saw of this ultimate standard product, where even the paint swatch was of Leyland s choice, LT took up an option to buy fifty more from a cancelled export order and then bought further batches of 110, 30 and 140 to bring the LS class to 437 members by the middle of 1980\. A year later the last MBAs and SMSs were replaced on Red Arrow services by sixty-nine new Leyland National 2s. Straightforward but reliable, the LS satisfied London Transport s single-deck needs for a decade and a half, often standing in for double-deckers when needed, and then going on to help hold the fort during the tough years of early tendering, during which some innovative LS operations introduced several new liveries and identities. The type served the ten years expected out of it with few worries, only starting to disappear when minibuses came on strength at the end of the 1980s. Although the LS was formally retired by 1992, refurbishment programmes gave survivors an extended lease of life, bringing us the National Greenway, the ultimate development of the Leyland National. Most of the Red Arrow National 2s thus became GLSs, and lasted until 2002. Matthew Wharmby is an author, photographer and editor specialising in London bus history. His published books include London Transport s Last Buses: Leyland Olympians L 1-263, Routemaster Requiem and Routemaster Retrospective (with Geoff Rixon), London Transport 1970-1984 (with R. C. Riley), The London Titan and The London Metrobus. He has also written many articles for Buses, Bus & Coach Preservation, Classic Bus and London Bus Magazine.