John Marshall operated as an optical instrument maker in London from at least 1685, until his death in 1723. Known primarily as a producer of microscopes and telescopes, Marshall seems to have spent much of his working life in or around the Ludgate Street area, which was near St Paul's Cathedral. His first workshop was known as the 'Two Golden Spectacles, Ludgate Street' and then the 'Archimedes & Two Golden Prospects'. Archimedes often featured in the shop signs and advertising of optical instrument makers, including competitors John Yarwell and later Willdey and Brandreth.

Later workshops in the 1690s and 1700s were known as the 'Archimedes and Golden Spectacles', or the 'Archimedes and Two Golden Spectacles'. A member of the Turners Guild from 1685, Marshall took a number of apprentices who would go on to become makers: Francis Hauksbee, George Willdey and Ralph Sterrop were amongst his apprentices and employees. Marshall's workshop output was not confined to telescopes and microscopes; he also advertised and is known to have sold magic lanterns, spectacles, burning glass and other glass-based objects of curiosity.

Marshall was may have been a supplier to the Royal courts of William and Mary and later Queen Mary. He included depictions of the royal coats of arms in his visual advertisements. In 1693, Marshall made what he claimed was a breakthrough in lens grinding technique (the precise nature of which has been lost) that allowed him to claim that he could make identical, high quality, batches of lenses. He was not granted a patent for his technique, but he did receive a letter of approval from the Royal Society, after examination by Edmund Halley and Robert Hooke, which would also feature in his advertisements.

Unfortunately, the lack of patent meant that copycat claims to the 'Royal Society approved' method of lens grinding flourished amongst Marshall's rivals, chiefly fellow telescope and microscope maker John Yarwell. In the early 1690s, a furious pamphlet war, where each denounced the other in printed advertisements, with a claim to be the inventor of the method. Some of these attacks and counter attacks in newspaper advertisements were personal and direct attacks.

When his employee George Willdey gained his freedom in 1702, he set up a rival workshop to Marshall's with a partner (Timothy Brandreth) they even took a similar shop sign, incorporating Archimedes, and faced their own attacks in print from John Yarwell.

Little is known about the later years of Marshall's life and career and it appears his output declined. A joint advertisement with Ralph Sterrop in 1707 may have been indication of a business arrangement, or simply the pooling of resources to advertise two makers in the Ludgate Street area. He died in 1723.