4079 Pendennis Castle is a 4-6-0 steam locomotive built in 1924 for the Great Western Railway (GWR) at Swindon Works to a design of Charles Collett.

Pendennis Castle gained initial notoriety in 1925, when it outperformed rival engines during trials on the London and North Eastern Railway.

[1] Back at Old Oak Common, it continued to run the routes to South Wales and the West Country until after the GWR was nationalised in 1948 to become part of British Railways.

While sitting at Westbury shed, bookshop owner Mike Higson, who was interested in purchasing a steam locomotive, was able to conclude a deal with British Railways to buy 4079 for £1,750.

[3] Following completion of its overhaul in March 1965, Pendennis Castle was transferred to Southall Railway Centre and appeared at one of the Great Western Society's (GWS) first open days.

[1] In November of that year, it became the last Castle engine to arrive at London Paddington before the end of steam traction on British Railways.

[1][6] On 29 May 1977, after hauling the Great Western Envoy from Birmingham to Didcot and return, 4079 headed to Avonmouth Docks where it departed for Sydney, where it was stored at Eveleigh Carriage Workshops.

[2][7] In the following March, 4079 travelled to Newcastle, New South Wales where it was loaded aboard the Iron Baron for Dampier, Western Australia, where Hamersley manager Ian Burston handed it over to the Pilbara Railways Historical Society.

[1][6][11] Adrian Lumley-Smith who was on secondment from Rio Tinto in London to Hamersley Iron became aware of the situation in 1998 when he moved to Perth and hatched the idea that 4079 should be relocated back to the UK and fully restored.

The pitch was successful, and a £37,500 grant from the Heritage Lottery Fund was quickly received and covered three-quarters of the costs to have it shipped to England.

[14] The restoration of 4079 at Didcot was carried out entirely by a group of 20 volunteers; manager Drew Fermor said they were determined to work at a high standard while minimising costs.

In addition, the GWS felt the costly installation of electronic equipment, and other modifications required for mainline running, would denigrate its original and authentic appearance.