Well - what it says, really.
My two sonatas together added up to just about 44 minutes when I timed them a couple of weeks ago, timing each movement separately and then adding about 2-3 minutes for time between movements etc.
This was, obviously, just about fine - it's LRSM, so 40 minutes +/- 10%.
However, on Wednesday, I had a lesson, in which the teacher slowed a couple of movements down a little - maybe 3, 4 clicks on the metronome. I'm concerned now (though I haven't actually timed, because I haven't yet got the speeds sorted in my head) that it's going to be outside the limit. If it is, it will be by about 1-2 minutes - no more.

What would be the penalty if I overran by a maximum of about 2 minutes?

Ugh. Panicking slightly. Have already cut out all the repeats except one set in the Brahms which I really don't want to get rid of for balance reasons, which only adds another minute, anyway...

You will be marked down if you overun, but I'm not sure by how much. Good luck in the exam

I have heard that it's a mark per minute over, although I suspect if you overran by many minutes, the penalty would be more serious...

I outstayed my welcome first time round - mainly due to a false start which rattled me and I had to take the time to calm down a bit... the Board wrote to me saying I hadn't been penalised this time, but that I should bear it in mind and sort it out for next time (I think the reason that they didn't penalise me is because I failed anyway). For my retake, I cut a few tuttis out to be on the safe side and played much better, passing by a good margin.

Please do time your whole recital - more than once. Consider cutting that last repeat if it makes a difference. Are you doing the exam on the piano? If you are, I suppose you can't cut tuttis!! Good luck.

Cutting your break between movements by 20 - 30 seconds would solve this problem quite easily. 2 to 3 minutes of break betweeen each movement seems quite excessive. But I'm a pianist and things may be different for you...

Sorry - I should have been clearer. I meant a total of 2/3 minutes added. I plan (especially now) to have as little gap as is musically possible.

I will run the sonatas at some point - it's just so exhausting to do! And not particularly helpful practice, given that my time is limited. I will also have a runthrough the week before and invite some friends along.

I think I'm in probable danger of overrunning - but by no more than a minute, 90 seconds. That should be okay, right...??

I might have overran my time in my ATCL performance last month, but only by a tiny bit. I don't think it's going to affect my mark much, because musicians, as understood by me, are quite flexible when it comes to timings and such. What's another 10 or 20 seconds of listening time? I think the examiner would be understanding. Anyway, I had already cut a lot of my breaks to about 10 seconds or so, and you should consider doing this.

In any case, you could just keep the speed for the movements which you feel comfortable with (be it slower, as your teacher suggested, or the same speed compared to your 1st timing).