Built in 1881 as a tavern, in the corner of a field known as 'Rocks Close'. The Rock is the first and oldest pub in Westham. The original building much of which has survived to this day was commisioned by John Groves & Sons Ltd of Hope Brewery, Hope Square, Weymouth and designed by G R Crickmay, a local and fairly prolific architect, responsible for the design of Stratton House, Dorchester former home to the West Dorset District Council and also in Dorchester, the Dorset County Museum. He also designed Purbeck House, Durlston Hall, Swanage Town Hall, The Great Globe all in Swanage.

Being the only public house in the area it became a focal point for the rapidly expanding community. A general meeting was convened at the pub in 1882 in order to agree a name for the area which was being built up around the pub. The name decided on was West Ham, now shortened to Westham (West'am, to the locals).