Riding four abreast in some cases can actually help cars to pass.
Technically, to pass a cyclist, you should do so exactly the same as you would pass a car. You have to perform a safe overtaking manoeuvre and you should not expect the cyclist to somehow get out of your way. After all - why should you dictate the speed that others should be travelling at ? Do you get out of the way of that 220mph Ferrari behind you ? Cyclists are not required to ride on the left hand side of the road (in some cases it is even dangerous to do so) and assertive riding (holding the lane) is often the best way to ensure safety (for example some idiots love to pass cyclists and then turn left into them - somehow expecting the cyclist to know they are doing this and give way.)
Road priority is generally on a first come first served basis unless the road signs/marking dictate otherwise. If you are behind a cyclist and cannot pass it you have no choice but to suck it up and wait. The cyclist has no reason or responsibility to get out of your way (do you expect slow people on stair cases to get out of your self-important way ? )
However, on single carriage roads, a long line of single file cyclists is almost impossible to pass because there are no gaps for you to safely filter back in to when passing. A group of cyclists could be passed in one overtaking move if they are tightly bunched.
Of course, these could have just been inconsiderate people. This doesn't mean all cyclists are inconsiderate and generalising about such things doesn't help anyone.
I went out for a proper ride on my bike the other week (2nd time in 3 years!) and, because of road works and the resulting opposing queue of traffic, it was impossible for cars to safely pass me. I'm doing, maybe, 15mph and a 4x4 half truck is behind me unable to pass - the lane is barely wide enough for his tank in the first place. After 20-30 seconds he decides his desire to get to the next set of traffic lights is more important than my life and passes me with no room for me whatsoever, whilst f'ing and blinding at me through the window. I ended up in the hedgerow. I could have easily ended up under his wheels.
I cycle with my daughter (now 7) to her school in the mornings (500yds at most). It's on the road we live on. It's a residential road with a normal 30 limit (residents have been petitioning for it to be a 20 for years as there is a school on it). Cars come down here at ridiculous speeds. Some pass me and my daughter (riding two abreast for her safety) whilst we are passing parked cars and there are cars coming in the opposite direction. Should we be stopping to let cars pass constantly ? Or should people just learn to respect other people's right to exist and chill out a little ? I guarantee that you will be waiting behind the car ahead at the next junction regardless of your urgency.
I have no problem sitting behind cyclists when I am driving. Generally I'm wishing I was riding with them. At worst, if I am delayed a couple of minutes, who cares ? I'm not driving an ambulance on an emergency or anything, you know, important.
People seem to be in a desperate rush to get to their graves. Relax and admire the view (especially if that's the Ladies Cycling club ahead of you
)