Basically what I'm asking is, are cars in the wrong by passing an indicating cyclist?
Theoretically yes, but don't expect a prosecution out of it. There's no habitual expectation and you could just be indicating to come out round a hazard.
Dominate the road a bit more. Ease out a little bit if you can, check your shoulder, look for a space, indicated, turn it into a thumbs up (as if you're grateful that they've agreed to give you a gap), pull across to the centre line and hold it until you need to turn. Most motorists will accept this kind of manouver gracefully.
Theoretically yes, but don't expect a prosecution out of it. There's no habitual expectation and you could just be indicating to come out round a hazard.
Dominate the road a bit more. Ease out a little bit if you can, check your shoulder, look for a space, indicated, turn it into a thumbs up (as if you're grateful that they've agreed to give you a gap), pull across to the centre line and hold it until you need to turn. Most motorists will accept this kind of manouver gracefully.