At the same time as the insurgency began in the south, in Aden, another revolution happened in the North Yemen. A group of republicans who were also followers of President Nasser overthrew the ruling royal family. Nasser then sent Egyptian troops to support the republicans.
Many in the British government wanted to recognise the new regime, but a small group in the security services, led by David Stirling, persuaded the Prime Minister, Harold MacMillan, to let them organise a covert war in the deserts and mountains of Yemen in support of the royal family.
These men had a romantic and simplified view of the world. They did not see this war as a nationalist struggle but as part of a much wider fight against a communist takeover of the world. Engaging in this global conflict would be a way of recapturing Britain's power and greatness.
The Islamism that we face today rose up in the 1970s precisely as a reaction to those corrupt regimes and their western backers. It too is an anti-colonial project that is very similar to Nasser's vision of a united Arab world free of western influence - but with religion bolted on. And now, to fight it, we are preparing to send arms and "intelligence advisers" to help prop up a corrupt regime in Yemen.
BBC - Adam Curtis Blog: YEMEN - THE RETURN OF OLD GHOSTS