The other customers - just two of them, both middle-aged blokes - sidle up as if we were old mates, showing the classic Irish gift of the gab (dictionary definition: the ability to speak easily in a way that makes people want to listen and believe you).
Pity about the believe bit. We get into the Guinness and, within a flow of yarns, Gerry explains how rats are a vital part of the flavour. You see, some of those early Guinness brews didn't taste so good and then, Hail Mary, along comes a keg of creamy nectar. When the brewers search for an explanation, they find dead rats in the mix - and from then on Guinness is fortified with rat bones. "It's true!" insists Gerry. "It's true!"
The barmaid laughs.
Gerry's mate is more direct: "We call him Gerry the liar."
Then, to confirm his status, the gentle fibber tells the tragic story of Paddy Murphy, the man who drowned after falling in a vat of Guinness. It took him seven hours to die - he kept getting out to go to the toilet.
But Gerry does have a plausible explanation of why Guinness tastes better in some pubs than others.
It's nothing to do with water from the Liffey, he says (just as well because it comes from the Wicklow Mountains), but it is to do with clean pipes and the distance the brew travels from keg to glass. Find a pub with a fastidious landlord and kegs handy to the tap and you'll be very happy.
We were always very happy in Ireland and can only assume the pipe lengths were just right and the sanitary habits of all the landlords impeccable.
It's not that we spent all our time in the pub, but you really do have to embrace the warmth, good humour and, in a land of troubadours, the music. If you don't know the choruses to Wild Rover and Dirty Old Town after a couple of nights, you're not taking it seriously enough.
For a chunk of the year, the Emerald Isle is an "inside" sort of place (inside by the fire, that is) and it seems incongruous that a land of historical deprivation should produce such sunny people.
The Galway cafe carries the sign: "Unattended children will be given a cappuccino and a kitten" and inside a waiter tells us, "Very good summer last year. I remember it well - it was on a Tuesday."
The radio DJs are forever optimistic: "There's a few showers coming, some of them heavy, and a lot of cloud. But otherwise it will be a nice, fine day."
The bad weather rap isn't entirely fair. Sure, it rains a lot, but you'd be unlucky not to have your share of sun if you made your move between April and the end of September.
But this is an outside land, too, and the rain, mist and wind are part of the mood. It's hard to imagine Yeats, Behan, and Joyce - and even grumpy old Van Morrison - sprouting from Ireland if the country had the climate of the Sunshine Coast.
Our mission in the republic and Northern Ireland was partly to explore family roots and we took the Wild Atlantic Way, starting at the dramatic Cliffs of Moher and clinging to the wilderness coast regions through Galway, Clifden, Westport, Easky, Sligo, Donegal and Ardara, before reaching Dunfanaghy in the far northwest. Then east to Derry, the Giant's Causeway and Belfast before winding back to Dublin.
The west coast is fantastic country if you like it rough and ready - at its peak the weather is testing but can be tamed by sun and blue skies. And there are always the people: wherever you are along narrow roads skirting tussock, lakes and streams, rock fences, pretty little houses strewn about like Lego, scrawny sheep, vast white-sand beaches and craggy headlands, and villages with the loveliest of harbours.
Everyone waves as you pass and, of course, you must not go to the pub unless you're up for a chat. In Clifden, big jovial Seamus Mannion sits in the pub that carries his family name, beneath a portrait of the grandfather who built it. Seamus, whose butchery is next door, picks the accent and we start talking the basics: meat and rugby.
He worries about his family's future in a country still doing it tough. Not too long ago he would sell 16 lambs a week; these days, it's just four. He once hoped his son would take over the business, but he has no interest.
It's an absorbing chat, and Seamus laughs through most of it, often at his engaging drinking mate, who glugs two pints of lager to my one of Guinness.
Why's he drinking Dutch lager when he could be enjoying Irish Guinness? Ah, it's all to do with a bad night of the black stuff a little while back. A long, complicated story.
What about the top shelf? "Oh, no," he says. "I don't do that. I never go there, never ... well, not usually."
Chocolate-box-pretty Ballywalter, on Ireland's east coast. Photo / Bruce Morris
And everyone falls about laughing.
At tiny Easky, home to my wife's forefathers in a region where Irish is still spoken, we head for an early evening drink and it takes us 30 minutes to get in the pub door.
We're intercepted by four locals at an outside table in the sun - genuine, welcoming folk fascinated, almost grateful, that people from a faraway land should come here to walk in the footsteps of their kin.
"You know," says one of them. "Your great, great, grandfather could have been a friend of my great, great grandfather."
When we reach Dunfanaghy, the wind is howling and the Atlantic is rearing up like an endless row of angry stallions, wonderfully inhospitable.
With names of my mother's family on headstones around us, we stand in the hilltop cemetery and begin to understand why folk headed for New Zealand 140-odd years ago.
It's early summer for us, but you could die of exposure up here. What a godforsaken place it must have been mid-winter in the 19th century without food to fill your belly and blankets to keep you warm.
Down at Molly's Bar, I squeeze in between a couple of locals, offering a "thanks, buddy" as one makes way.
"Buddy?" he asks. "No one says that here - you must be from Dublin or somewhere?"
Like his Easky countrymen, he's moved that someone would travel around the world to his backyard to pin leaves to a family tree.
"I've got something I want you to have," he says.
"A fossil shaped like a heart I found on the beach. I don't know what it means, but I think it could mean you'll come back here if I give it to you."
I don't want to sound ungracious, but wonder if it might be more treasured by someone who's been in his affections longer than five minutes. Besides, I suggest, it may mean nothing at all.
"You're right," he says.
"It probably means nothing at all. I'll give it to someone else."
It's a very Irish moment, a chat about nothing going nowhere, all conducted in gentle warmth and ending up lost in the chorus of Wild Rover.
Anyone who explores Ireland will return with stories to remember, even some ringing of home.
Music and craic in Galway. Photo / Bruce Morris
At Mullaghmore harbour in Donegal Bay - as far away as it's possible to get from New Zealand - we find a charter boat named Kiwi Girl.
There isn't time to discover the story behind that geographic oddity and the lack of response to subsequent emails suggests it's a tale that will stay hidden, perhaps for good reason.
As we meander down the coast towards Dublin, we stop at Ballywalter, another of those charming little fishing villages made for chocolate-box covers, and talk to a man who's laying out seaweed to dry in the sun. Dulse, it's called, part of the local diet.
He's not certain of our accents, but brightens up as you'd expect when we tell him we're Aucklanders and not Australians.
"Ponsonby!" he declares.
"John St, Ponsonby - do you know it?"
Of course we do. My wife grew up just around the corner.
Our dulse man was a seaman in the 70s and loved his Auckland stopovers almost as much as he loved the girls and the parties at the old villa in John St. He's delighted to share the memories.
Ah, the things you discover when you stop for a natter, and we walk off with a smile on our faces; his is even wider. It's always the people that make the difference.
Bruce Morris travelled in Ireland and Northern Ireland with help from Tourism Ireland.
