He obtained a grant from a fund originally set up by the organisers of the 1851 Great Exhibition, and secured a job as an assistant tester in the engine test houses of Rolls-Royce Limited at Derby on 13 July 1925.

His design work continued with development of the Merlin, and he was a major contributor to the success of the Rolls-Royce Griffon, the last of the V12 piston engine line.

During his time at Rolls-Royce, Rubbra married his secretary, Lilian Webster, and in 1961 he was appointed a Commander of the Order of the British Empire (CBE),[5][6] as was his brother Edmund who was a respected musical composer.

In 1969 he was awarded the Royal Aeronautical Society's highest honour, the Gold Medal for 'outstanding contributions over many years in the whole field of aircraft propulsion'.

His services were required once more in 1971 when he was asked, along with Stanley Hooker, to assist with developmental problems pertaining to the Rolls-Royce RB211 civil turbofan project.