The neighbouring Radcliffe Infirmary was keen to expand its buildings, and there was no room for the large enclosure that would be required for any new telescope.

Before becoming Radcliffe Observer, Knox-Shaw had served at the Helwan Observatory in Egypt, where he came to appreciate the benefits of siting a telescope in an arid area.

[7] This telescope would have four times the collecting area of the next largest in the world, and would easily outperform anything that the Radcliffe Observatory could construct.

[3] With the offer of funding in place, in 1929 the Radcliffe Trust asked the Astronomer Royal, Sir Frank Dyson, to assess Knox-Shaw's proposal.

[3][10] They took this opportunity to examine several possible sites in the country for the new observatory, deciding that the most favourable was one located on a range of hills near the city of Pretoria.

[3][10] The local Municipality of Pretoria was strongly supportive, offering to donate the land and connect it to the water and electricity distribution systems for free.

[4] The site occupied an area of 57 acres (23 ha) on the Kiapperkop ridge of hills 4.5 miles (7.2 km) south-east of the city.

Grubb Parsons proposed building a copy of the 74 in (1.9 m) telescope they had produced for David Dunlap Observatory in Canada, which was then under construction (it would be completed in 1935).

The main outstanding item was the polishing and installation of the primary mirror, which was still at the Grubb Parsons factory in Newcastle-upon-Tyne.

Grubb Parsons was required to shift its work to military purposes (they were the major source of British submarine periscopes), and the industrial areas of Newcastle were now a target for strategic bombing.

[3] Thackeray had previously worked at the Solar Physics Laboratory, Cambridge and the Mount Wilson Observatory, California, and had collaborated closely with Arthur Eddington.

[11] At the time of Thackeray's appointment, there was only one other astronomer on the staff of the Radcliffe Observatory, the Second Assistant David Stanley Evans.

[11] Michael Feast was appointed as the new Chief Assistant in 1951, at which point Evans left and was replaced by Adriaan Jan Wesselink.

[11] Some technical staff were also transferred to Pretoria from the Royal Greenwich Observatory, to provide support for visiting astronomers.