It is the responsibility to the StRs to check with each lecturer a couple of weeks before the lecture, to confirm the time and place of the seminar. It is probably advisable for a single StR in the year to take on responsibility to see that this happens.
If a seminar has to be cancelled at short notice, it is the StRs responsibility to try to find an alternative lecturer (consultant or Year 4/5/6 StR), and let Gavin Stoddart and Dom Fay know what has occurred.