When, if ever, is it OK to ask a famous person for a selfie? I was faced with this very modern dilemma at the weekend when a global sporting superstar sat down just a few feet away. It’s not the quandary one necessarily expects when having a drink in Dalmarnock, but I was at the Emirates Arena having watched Andy Murray put Great Britain into the final of the Davis Cup for the first time since 1978.

The scintillating tennis and electric atmosphere had already made this the most thrilling Sunday afternoon ever. My companion and I were enjoying some post-match hospitality and still buzzing from the match when Murray sauntered in to join his family, who were sitting a couple of tables away. The statuesque Scot gave his granny a bear hug, then his mum, then his wife. It was a lovely moment.

My friend and I swung round to face each other: should we ask our sporting hero for a picture? We ran through some selfie etiquette, blushing at the thought of approaching him. Was it acceptable to interrupt family time? Would we come across like a pair of daft teenagers at a One Direction concert?

My mind went back to the last time I was in such a situation, 20 years before in a London pub when I spied Morrissey. The Smiths were always my band, and seeing their singer in the flesh almost made me lose control of my bladder. These were the days before mobile phones, of course, and I didn’t even have a scrap of paper or a pen to ask for an autograph. If I approached him, I would have to start some sort of actual conversation. I remember breaking out in a cold sweat at the thought.

Morrissey, master of the withering put-down, is known for wanting to be alone - in the Greta Garbo sense. I pictured him sending me packing with an epigram before I’d managed to stammer any words out. Was it worth risking my pure, unsullied love of The Smiths for one short, never to be lived down moment with my idol? Before I had the chance to decide, I looked up and he was gone.

Back at the Emirates, 20 years older and wiser, I grasped the nettle and approached Murray as he got up to leave. He was hurrying to catch a plane, he told us in that much-mimicked baritone, but happy to pose for a quick selfie. Nice one, Andy.

The resulting picture is shambolically composed but will no doubt make my friend and I smile for years to come. Sometimes I love modern technology.