John Penn FRS (1805–1878) was an English marine engineer whose firm was pre-eminent in the middle of the 19th century due to his innovations in engine and propeller systems, which led his firm to be the major supplier to the Royal Navy as it made the transition from sail to steam power.

[1] The senior John Penn had in 1799 started an agricultural engineering business on the site at the junction of Blackheath and Lewisham Roads (close to modern-day Deptford Bridge).

Although John Penn senior lived in Lewisham he stood as a reformist candidate for Greenwich in the December 1832 parliamentary election.

[2] His enhanced reputation due to this notable advancement was further augmented by Penn's introduction of trunk engines for driving screw propellers in vessels of war.

[2] These advancements were coupled with a reputation for quality and reliability and this led to Penn becoming the major engine supplier to the Royal Navy as it made the transition from sail to steam.

[2] Penn was also responsible for introducing wood bearings for screw-propeller shafts which became vital to the worldwide use of steam-powered ships.

He took them to pieces and he distributed the parts among the best machine shops in the country, telling each to make ninety sets exactly in all respects to the sample.

Built (or assembled) in 1861, it is the only known example, and in being recovered intact was found to have all its fittings and fixtures attached including Penn's nameplate.

[4] In June 1859 he was elected a Fellow of the Royal Society; the citation said: John Penn CE (Civil Engineer).

Sopwith, Joseph Whitworth; Rob Stephenson and others.In 1860 Penn was a founder member of the Royal Institution of Naval Architects.

[3] Aside from the advancements made in marine engineering, John Penn is remembered in Greenwich through street names and buildings.

He is also represented in Deptford, such as the arched riverfront of the boiler works, and in Lee, south of Blackheath, John Penn's grand house The Cedars still stands, although now converted into flats.