Riding home along the A4 towards Maidenhead, approaching the Thames bridge after which I would turn right to Cookham. Usual queue of stationary/ stop start traffic, which I am filtering along the right side, using the gaps in the oncoming traffic to make progress. I had passed an MTB with panniers, keeping with the traffic flow, about 500 yards previously and said hello to the rider. He said hello back.
Anyway, vehicle are moving at about 12-15 MPH so I am sitting to the right of the lane, just off the rear offside corner of the car in front of me, holding my position. The queue slows so I start to pass and continue filtering on the right. I then hear what I can only describe as a skwawk from behind me. i look and the MTB is right on my shoulder setting to pass me as I pass the cars. he is nearly forced into oncoming traffic. I brake and move left to give him room and he continues past, pulling ahead of the cars, into a gap wher he moves into the left side of the lane to go straight ahead. I pull into the same gap, setting to turn right at the roundabout. I say- nearly had you there- sorry! to which he laughs then continues on his way.
I was cross with myself for not seeing him and nearly getting him hurt/ killed but now I think about it, I'm not so sure he wasn't being a bit dodgy by trying to pass me without warning when he did. To my mind, my positioning made it clear that my intentions were to continue filtering on the right