Leading a minute's silence - practicalities and protocol?

[methyme]

I have to chair a formal meeting tomorrow (stepping in for the usual Chair), which will start with a minute's silence. I don't wear a watch, not sure if there will be a clock in the room, and don't want to use my phone clock. I was thinking of counting to 60 in my head, which will be approximately right. But there will be some traditionalists around the table - might they be offended if it's not exactly a minute, and are there any other protocols I should be aware of?

Why not use your phone clock?

Just use your phone clock

Will you have a laptop?

If not, is there someone taking minutes? Can you ask them to indicate when the 60 seconds is up? Seems more formal than asking another member of the meeting.

Because it's a "phones off the table" sort of a meeting.

Well you put your phone away after the minutes silence. Or you buy a watch!

Can someone at the back of the room give you a discreet nod?