That was a British Interplanetary Society (BIS) concept. In the 70s. Using technology that hadn't yet been invented yet but that was considered possible, to try and work how to develop an *interstellar* spaceship. The idea was to mine Jupiter or its moons for Deuterium and use fusion. Not really a practical idea, yet, or probably for some centuries, even if the whole world backed it.
Project Orion, the Dyson version, does seem possible, with enough government money.
How about this idea: France joins Commonwealth in 1950s, and eventually moving to a merger with the UK. No French nuclear program - just a combined UK/French program. No Force de Frappe. No Concorde. But yes an Anglo-French Orion !?! (what name?)