Thanks for the reply, Cubist.
It turned out when I went back to the job yesterday when there was a bit more daylight only one of the connectors was hard to remove. As you suggested you have to push down a tab on each connector to release it.

I have purchased a secondhand rear electronic module as it seems from other posts that this is probably the cause of my faulty RH rear indicator. I have started to replace the module. The multiway connectors seem difficult to remove. Has anyone got any tips for removing and replacing these as I don'...