Cookson was selected for the British Isles on the 1899 tour of Australia playing in all four Test matches.
[2] In 1899 he was approached by Matthew Mullineux to join the British Isles rugby tour of Australia.
[3] In the first Test he was partnered at centre with the tour captain, Mullineux, but after the team was defeated, Mullineux dropped himself from the team, bringing in Charlie Adamson from three-quarters to team-up with Cookson for the final three Tests.
The selection tactic proved successful with the British winning the remaining contests with the Australian side.
On returning to Britain, Cookson continued to represent Manchester and in 1900 was invited to join British touring team the Barbarians.