Due to Britain's withdrawal in 1968, ELDO in June 1969 had other ideas than staying with the Blue Streak launcher for Europa's first stage, to give technical work to countries that were still (loyally) part of the organisation. Unfortunately, few other European countries had sufficiently advanced technical knowledge of rockets at that time. The Blue Streak had worked much more successfully than the other engine stages. Nonetheless Blue Streak, ELDO's most successful rocket to that date, was replaced. On 28 April 1970 at a meeting in Paris, ELDO replaced the Blue Streak with the French-made Diamant. Britain's most significant involvement with the project came to an end. The following year Britain would put its own rocket programme, Black Arrow, (prematurely) out of operation.