I would say the filter lane aspect is irrelevant; if on a multi lane road , traffic is moving in lanes and the lane on the left is flowing faster than the lane on the right , it is perfectly permissible to pass traffic moving more slowly in the lane to the right .Okay, one for you that I've been meaning to ask for while since it happened though never got round to it.
Say lane one is a dedicated filter lane for leaving at the next junction. Can you undertake traffic that intends to remain on the motorway in lane two?
The example I use is the M25 clockwise, A3 turnoff, where the filter lane is over(?) a mile long. I was in the filter lane, and slowed to keep pace with an HGV in lane 2, remaining on his rear 3/4. My take on it was that it's just another lane on the motorway, and as such you'd be considered for the offence of overtaking on the inside lane. The views of the line of traffic that built up behind me cast doubts on my assumption. Roads were clear, no lines of traffic waiting, all flowing nicely.
The rage of the Cavalier driver with family in tow was tangible. I could literally see his spittle hitting the inside of his windscreen. I could see it because he was hanging onto my rear bumper like a bad case of the clap. Anyway, lots of people overtaking the hgv and en masse returning to lane 1 passing traffic on the right at 70.
What do you think? I've just read the HC on leaving a motorway and it doesn't deal with filter lanes.
Time to cover one mile @ 56mph = 64.29 seconds
Time to cover one mile @ 70mph = 51.43 seconds
Time saved by overtaking to get to the traffic lights quicker = 12.86 seconds
I would just keep a watchful eye for the lazy of thought who make a last minute lane change but other than that it is fine .
If the lane markings have changed from normal ones to long dashes with short gaps , then it no longer counts as a running lane on the motorway and is now the exit lane , so your concern does not apply .
Either way , it is fine .