A 25-year deal has been signed to strengthen the Swanage Railway’s locomotive fleet in a move that will see three classic 1920s Southern engines based on the Dorset heritage line – one of which ran in the Isle of Purbeck back in the 1950s.

The contract with Hampshire locomotive owner John Bunch covers three Southern Railway Richard Maunsell-designed locomotives, with ‘U’ class No. 31806 set to arrive at Swanage and start work hauling trains on the award-winning relaid Purbeck Line during August of this year.

Built at Brighton and the only surviving rebuild of a River class locomotive, the ‘U’ class – nick-named a ‘U-boat’ – has seven years remaining on its boiler certificate and visited the Swanage Railway earlier this year and in September last year.

The other two steam locomotives covered by the deal are complete and await overhaul before they can be used – the only surviving ‘N’ class, No. 31874 built in 1925, to be returned to traffic first and then ‘U’ class No. 31625 built in 1929 which will be the second of the two locomotives to be overhauled.

Swanage Railway Company chairman Peter Sills said: “These three classic 1920s Southern Railway steam locomotives are highly appropriate for the Swanage Railway and will strengthen our existing locomotive fleet and provide an exciting balance of available motive power suiting the power and economy requirements of our developing line.

“No. 31806 used to run down to Corfe Castle and Swanage during the British Railways days of the 1950s and is the quintessential Southern Railway branch line locomotive.

“The three Southern Railway locomotives will give the Swanage Railway a balanced and exciting locomotive fleet – and complement the two 1940s Bullied Pacifics, a 1950s Standard Tank, the Victorian-designed Drummond M7 tank and a Great Western Railway tank locomotive which haul trains on the Purbeck line,” he added.

The ‘N’ class locomotives No. 31874 and the ‘U’ class No. 31625 are set to arrive on the Swanage Railway in late June or early July this year.

No. 31874 last hauled a train in 1997 and is the only surviving ‘N’ class locomotive – and also the only steam locomotive built at the Woolwich Arsenal in London to survive.

It is planned to have No. 31874 overhauled and ready for traffic by August, 2015.

No. 31625 last hauled a train in 2001 and is the only ‘U’ class locomotive with a British Railways modified front end.

It is planned to have the locomotive overhauled and ready for traffic by the winter of 2016 or the spring of 2017.

Details of Swanage Railway train times – and special event details – are available online at swanagerailway.co.uk or by calling 01929 425800.