It’s a rare band that reaches its half century. The Stones, obviously.  The Who, albeit down a couple of men. But usually it’s a feat reserved for the great American soul/gospel franchises – the Dixie Hummingbirds, the Blind Boys of Alabama – that just replace members as they fall off the perch, music’s very own Ships of Theseus. Fairport’s golden anniversary is therefore deserving of a mighty celebration, and gets one here tonight at the Old Fruitmarket for Celtic Connections.

They greet their 50th with only one member, Simon Nicol, still in place from that debut gig –  St Michael’s Church Hall in Golders Green on 27 May 1967 – but otherwise a line up that has clocked up over 150 years service between them.

Their support tonight is folk royalty too. Liverpool-born Steve Tilston and County Durham’s Jez Lowe have joined together on a project showcasing both their talents. Each man’s music bears the hallmark of their homelands. Lowe’s display a caustic North Eastern edge, Tilston’s exhibit a Liverpool melodiousness. The audience hardly give this rich, considered music the reception it deserves, though. “In the north of England, we sing along with the chorus. Can you do that?” prompts Lowe, amiably introducing The Wagga Moon. It seems not. At least not in this part of the Fruitmarket. It’s perhaps taking them a while to warm up. There is a warmer response to The Strings That Wizz Once Strummed which pays fond homage to another folk legend, Wizz Jones.

Everyone is more voluble for the main feature, though. Scottish traditional music organisation, Hands Up For Trad, introduce the five, presenting them with a Landmark Award. All smiles, they’re still not the sort to over-indulge. It is, insists Nicol, “another day at the office.”

Fairport’s early brilliance has also always been their curse. Whatever they have done or will do – and their relatively stable post-1985 set-up has claims to greatness in its own right – they will always be haunted by the members, living and dead, that are no longer with them. That late 60s incarnation burnt so brightly, yet so briefly, with such an array of musical talent, it casts a permanent shadow. With Richard Thompson, Sandy Denny and Dave Swarbrick on board, they were to folk what Page/Plant/Jones/Bonham is to rock, or the Miles Davis Quintet is to jazz.

While Denny surprisingly doesn’t get a mention, the other two’s works are inescapable. “We were always disguising new songs as centuries old. This one started off new and is now traditional,” says Nicol, very accurately, of Thompson/Swarbrick number Crazy Man Michael. “Neither man is here tonight but their spirit could be.” Swarb of course was another of the Reaper’s 2016 victims.

But it’s not all about harking back to their roots. Recent material pays its way too. Chris Leslie retains both the hairstyle and the voice of a younger man and on the likes of Myths and Heroes it combines with chugging guitars to show the modern band to good effect.

The mid-80s were fertile times too, represented well here by the melancholic Hiring Fair and the bonnie instrumental Portmeirion.

Quite what Fairport of ’67 would have thought about doing a song about DIY (Devil’s Work off the new album) though, we can only speculate. One hopes they might have thought better of it.

It’s too brief and Tuesday night-y to be a truly great Fairport gig, with too many bases there’s not time to cover. They plug their annual Cropredy shindig extensively, and a balmy English summer evening is their ideal setting. But even in a Glasgow January, it’s good to see them. Here’s to the Convention rolling on and on for many summers to come.