Quoting Andrew Fife (afife@untangle.com):
We just don't have a regular membership who will turn up regardless of the speaker... maybe this applies to 3-5 people but their all on the mailing lists anyway.
IMO, this is a compelling argument. A good measure to protect in case it's at least in part mistaken is to at least attempt to talk the Four Seas Restaurant staff into briefing anyone who arrives on the wrong day.
This is most likely to have the desired results if you give the manager a (really short) flyer/notice, to show to people.
In general, waiters and busboys aren't going to give a rat's ass about the details, and at best are going to say "Sorry, not here" without giving even a hint what happened. Giving the manager a written notice makes it at least possible that something better will happen.
Anyone who shows up on the original date will likely check the website, realize _THEIR_ mistake and likely decide to come the following week...
Yet another reason for my own strategy about upcoming-event scheules: If a scheduled event has to move to a new date, you _don't_ remove entirely the schedule item for the old date: Instead, you put it in <em> tags and make it cross-refer people to the replacement date (e.g., "has been rescheduled to...".
I mention this because a lot of LUGs tend to just remove old event listings completely -- which is unfortunately a disservice to anyone who's already seen them and made plans. Much better to retain the event and mark it for the public's attention as _no longer_ the date on which that event will occur.