The might have a business to run, but that is the perfect reason for them to let you have a few minutes in the chair. It would have cost the nothing in real terms and the value in goodwill would have been priceless for a shop like that.
I've taken a shave there and the place was not exactly packed, to say the least. On top of that I don't believe the barber that gives shaves is even there everyday. At least that is what I was told I made my appointment. I doubt you would have been keeping anyone out of that chair.
Good luck with the search for a photo spot and your upcoming nuptials.
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