He showed me a black-and-white photograph, circa 1959, of a bleak office in the grounds of Dublin Castle. Outside the door was a broken plastic chair listing on its metal legs and, above it, a sign that clearly read “Aliens’ Office”.

He had had to register there when he arrived and to return every six months to confirm his continued presence in Dublin, a city he had travelled to on the advice of the merchant seamen he met in Rotterdam, men who had told him that its streets were rife with red-headed women, two at least, they said, to every one man. It was a city on a bay, cradled by mountains and freckled sirens, compelling enough temptations for a restless young man tired of a more predictable Dutch landscape.

We were having lunch. His leather hat sat on the linen cloth. It was a reunion of sorts: him, my sister and me. The waiter was young, jittery; he shook out the starched napkin and placed it on my lap. A change, certainly, from lunching by the cooker with a pot of last night’s gloop in one hand and a fork in the other.

When my friend first arrived, on the cusp of the 1960s, there were buses on Grafton Street and people in low-slung bars blowing smoke rings at the ceiling. A few years later, basement boutiques selling psychedelic bell-bottoms mushroomed on the street, next to the Dandelion Market, where kaftans and scratchy singles were peddled to skinny boys and girls, their jeans held up with woven crisses.

Where are all the redheads?

There were, my friend noted, fewer women than had been promised in Dublin, and not all redheads either.

“I’m sure there were ample,” I suggest through a cradle of samphire.

My friend – an immigrant to Ireland, arriving as swathes left, weighting down the mailboats for England – was a good-looking, humorous, inquisitive young man with a van Dyck beard. He recalls travelling on a Dublin bus and his knee inadvertently touching the nylon-clad leg of the woman next to him. She blessed herself; he was startled. It happened again a couple of miles on, and he realised it wasn’t his dancing continental knee but the passing of churches that was causing her to cross herself.

A hairdresser by profession, he knew how things might look with a little adjustment. He sensed change in the air, an opportunity to slip out from under the thumb of the back-combs and barrel cuts.

He opened the first unisex hair salon in the city, Herman’s Klip Joint, a shop that survives on Grafton Street, where it started. It would never work, they told Herman, men and women having their hair cut side by side. Unseemly.

But it did. There was “no sex discrimination at Herman’s”; regardless of gender, a haircut cost you about a fiver. Couples queued together on the stairs, and my sister, who worked there in the early 1970s, recalled stepping over their platform shoes to get inside. The first-floor window of the shop could be pushed open on to Grafton Street, and music played from the sill. A couch materialised and a life-sized cardboard Marilyn in a Playboy pose.

Phil Lynott turned up; a flat comb was found. Bands such as Horslips wandered in. Performers from shows around town mounted the linoleum stairs, the casts of Cabaret and Hair. Jim Fitzpatrick designed the ads, though the slogan “Feel like having it off?” was refused by newspapers. Herman’s Klip Joint was the home of a small revolution.

I listened to them talk, remembered being 10, perched on the edge of that couch clutching a Brazil nut bar, waiting for my sister to finish her shift and take me to the pictures.

I remembered glimpsing that extraordinary world, so distant from the monochrome suburb on the other end of the bus route. It was a parallel reality, a world I coveted and whose details I hoarded.

Lunch was over, and our jittery waiter removed the plates. Herman’s food was half-eaten; a raconteur, his stories were more compelling than the sea bass.

“Do you ever feel like an alien now?” I asked him. “After a lifetime in this city?’

“Dat mag niet,” he replied, Dutch for “that is not allowed”, a phrase he often encountered in the country of his birth.

“I came here,” he said, smiling, “maybe got a little drunk after a long week. ‘That’s allowed’, they said to me, ‘that’s allowed’.”

It was all allowed. It is all remembered. All still tinting the ether.