As can be seen from the table below, it was only in about 1840 that the eponymous James Gill (1814–1879) entered into business with the current owner, James Pilcher, at 5 High Street. Within a couple of years Pilcher gave up the business to James Gill and George Ward, younger brother of the Oxford Mayor William Ward and probably James’s relation.

The firm has occupied five different shops in the High. The ironmonger Bush is first listed in the High Street in 1816, but was probably also there in the eighteenth century, and No. 5 is first specified in 1839. Business must have gone well for Gill & Co. in the latter half of the nineteenth century, because in 1891 they expanded into No 4 next door.

In 1922 Barlow & Alden Ltd and Ison, Kidman & Watts amalgamated under the name of Gill & Co. Ltd; and in 1923 Gills retreated back in No. 5. But when Sainsbury’s at No. 4 expanded into No. 5 in 1925, they moved across the road to Nos. 127–8.

In about 1953 Gill & Co moved to its present smaller premises at the rear of their shop, which were given the number 128A High Street. At this date they were described as "ironmongers, heating engineers & plumbers".