It is now managed by the Isles of Scilly Wildlife Trust, and except for the maintenance of the Grade II listed lighthouse, landing is not allowed.

It was built by Chance Brothers & Co of Birmingham and, said at the time, to be ″ .... in relation both to size and character .... the most remarkable works of their kind hitherto achieved.″ A similar optic had been installed in the nearby Bishop Rock Lighthouse the previous year.

[10] Mineral oil for the lamps was stored in tanks, located at the south end of the island alongside the aerial host.

[13] Britain's first wireless beacon for navigation, designed for Trinity House by the Marconi Company, was established at Round Island Lighthouse in 1927,[14] (following the trial run of an experimental system there two years earlier).

It automatically transmitted a repeated cycle, including the station's unique call sign ('GGG' in Morse code), for nine minutes every half hour (or continuously in foggy weather).

[8] The old hyperradial optic was replaced by a flat vertical panel with rows of sealed beam lamps, each covered by a red shade,[17] which was mounted on an AGA revolving gearless pedestal.

[18] A helicopter pad was built on the rock alongside the lighthouse in 1969, but boat deliveries also continued;[10] the aerial hoist was upgraded in 1972.

[19] The lighthouse continues to display one white flash every ten seconds; the 360 millimetres (14 in) revolving drum optic[20] has an intensity of 42,945 candela and a range of 18 nautical miles (33 km; 21 mi).

[22] Breeding storm–petrels were unrecorded on Round Island for many years, until one of the lighthouse keepers, mystified by the nightly appearance of black feathers in the living quarters, decided to keep some.

[27][28] On the last couple of trips to remove the rats, teeth marks of the Scilly shrew (Crocidura suaveolens) were found on non-toxic chocolate wax.

Thirty years later, in 1987, Rosemary Parslow found much of the ground between the buildings and the cliff edge was covered in a carpet of purple dewplant (Disphyma crassifolium) and Hottentot fig.