Intrigued by the genius of AI, I typed in "British Empire in space, Union Jack, stars," half expecting a scene from Grand Zimbabwe on the Moon, but no, out came a pretty creditable Imperial Fleet Station. But what about "Imperial British Space Navy in battle"?
Not bad! Inspirational, in fact, and here's another:
Join up, boys, and see the stars.
For King and Country. Speaking of which, here's Lord Curzon, on the sands of Mars:
And it's Tommy this and Tommy that:
Stand strong, soldier, for the Empire.
Ad Astra,
LSP