I sent out an email this morning, to let people know that I'd be out of the office, which actually generated a good number of student research enquiries - far more than I'd usually get on a Friday in the library, which tends to be quite quiet at this point in the semester.
When I'm visible in the London Centre, I'm only visible to other people in the same space - online - no boundaries. I suspect at least one or two of the enquiries I answered today came from students who are travelling this weekend, and history would suggest they wouldn't have thought to email me without the prompt.
The vast majority of the resources I was locating for people were online-access, and many of the books were via ILL, which means they wouldn't be available until next week even if I'd been working out of the office, so I think that was a net win (plus, my house isn't fixed, but we're a stp closer, at least!)
* Photo by HTYYL, used under Creative Commons, with thanks.