I don’t think I’ve seen The 4 Of Us live since their glory days back in the late Eighties/Early Nineties, so I wasn’t sure what to expect from the Murphy brothers – “there are four of us, counting the two guitars”. I do know from personal experience that Declan Murphy is a thoroughly decent chap and his singing brother Brendan proves himself to be a most engaging presence this evening, talking us through songs from their 2016 album, Sugar Island, offering a potted history of the brothers’ upbringing in Newry against the backdrop of the troubles. The record is, as Murphy describes it, “A concept album about growing up in a colourful period” and songs like ‘Bird’s Eye View’, ‘Sugar Island’, ‘Hometown On The Boarder’, and the family-going-on-holiday-listening-to-Mungo-Jerry-through-the-checkpoints ‘Going South’ all deserve to be more widely heard. Those songs, the delicate and sympathetic instrumental interplay, and Brendan Murphy’s patter – remembrances of buying records and teenage love, gently taking the piss out of his brother for daring to get funky with red hair – all make for a warm performance, winning a lot of us who might have underestimated them – me included - back over. I won’t be leaving it as long again.

You can say what you like about Robert Plant, but he goes where the muse takes him. He could be out making enough money to buy himself a children’s hospital in Kilmainham every night, but he's long since turned his back on all that. “My peers may flirt with cabaret, some fake the rebel yell, I’m moving on the higher ground” he sang on ‘Tin Pan Valley’ from 2005’s Mighty Rearranger’, an album that carried on the purple patch begun with 2002’s Dreamland, a sterling run that has continued to this day. It would of course be a huge thrill to see Zeppelin knock out the hits in some enormo-dome - although let me stick my head above the parapet and say that the longer the Celebration Day reunion show went on, the colder I found it. I might of course be singing a different tune had I been lucky to enough to get a ticket, I did see Page and Plant play in the nineties and that was spectacularly awesome - but Plant is still searching for something else. If Jimmy Page is sat waiting by the phone, then he should make himself comfortable because it’s not likely to ring anytime soon.

The stage in this beautiful room is dark, the definition of moody lighting, accurately reflecting the other/olde worldliness of the music of the “co-operative" Saving Grace. Vocalist – far too small a word as it will turn out – Suzi Dian stands alone at the mic, in front of the almost tribal beat that Oli Jefferson is coaxing from his drums. To her right sit Matt Worley and Tony Kelsey, picking the low notes out on two baritone – slightly longer neck, allowing for lower tuning – guitars. Plant himself doesn’t appear until about half way into the rumble of Patty Griffin’s ‘Standing’, perhaps a ploy to allow the audience to appreciate how great this small unit sounds without any howling for yer man outta the Zeppelin. When he does emerge into the spotlight he slips seamlessly in, his voice combining with Worley and Kesley’s to prop up Dian, not that she needs it. Plant gives a gentle shake as Worley, now on banjo, leads us into ‘Satan, Your Kingdom Must Come Down’, a song as old as the oldest hills,  a version of which can be found on 2010’s Band Of Joy record. Jefferson picks up the pace with a  military tattoo, Plant grabs a tambourine, as does Dian, and the song segues into ‘In My Time Of Dying’. This, as it turns out, is the only thing even approaching Led weight this evening, but it’s a long way from the bombast of Physical Graffiti. Plant’s voice has rarely, if ever, had less to hide behind, but it’s more than equal to the task.

The band have been on a four corners tour of Ireland over the last week – Galway, Waterford, Kilkenny (Brendan Morrissey gushes, bright-eyed, about the Set Theatre performance in the bar before the show), Cork, and Belfast – and Plant has obviously been having a ball travelling through our “remarkable land, there wasn’t a dry eye in the house or a sober person anywhere we’ve left”. He promises us songs from “behind the trees, in the hills, and on the tops of mountains” and the following ‘Cuckoo’ certainly fits the bill. There’s a version in the Bodleian Library in Oxford going back as far as the late Eighteenth century but it most likely goes a lot further into the mists than that. The combined banjo and mandolin work of Worley and Kelsey -  if it has strings attached, these two men can get something out of it – picks out a riff that Plant used on ‘Little Maggie’ from lullaby and… The Ceaseless Roar, but that song stretches beyond The Stanley Brothers’ 1946 version into a distant Appalachian past, so it’s fair game.

Jefferson’s brushed drums take us into Blind Willie Johnson’s ‘Soul Of A Man’. Johnson first put it on wax around 1930 and it recently surfaced again in a cracking, and cracked, version from fellow musical oddball/scholar Tom Waits. Worley takes the vocal on the verses, joined by the others for the “won’t somebody tell me” refrain. Plant slips a harmonica from his pocket and adds a few low notes. He had stumbled slightly by introducing the wrong song earlier so he continues now with the story of a charmed life looking, exploring and searching through music. He’s spent time living in America over the last few years learning more about the songs that were brought from Europe to the States such as ‘Your Long Journey’ which should be familiar to all from his collaboration with Alison Krauss on Raising Sand. Plant possibly first heard it from Doc Watson. The hypnotic bluegrass harmonising is another showcase for Dian’s beautiful voice.

Plant goes deep again. We hear about Bascom Lamar Lunsford, who travelled around the Carolinas in the early part of the twentieth century collecting songs in remote locales. He did a bit of performing too, earning himself the sobriquet “Minstrel of the Appalachians”. Jefferson’s floor-tom beat – there’s no bass player so, as well as the baritone guitar work, it seems, to me at least, that the bass drum and toms are more closely miked to fill things out – opens ‘Cindy, I Will Marry You’, a song Plant took from Lunsford’s collection and adapted ever so slightly. Kesley takes an actual guitar solo but he’s far too tasteful to get carried away. Plant is nothing if not catholic in his tastes so a keyboard drone – Worley on what looks like a Casio’s ancestor – kicks off ‘She Cried’, originally a hit for Jay and the Americans in 1962, although this troupe succeed in making it sound like something from 1762. They perform a similar feat with Moby Grape’s ‘It’s A Beautiful Day Today’. Plant has been banging on about The Grape for decades, the curious should check out his version of their ‘Seeing’ (aka ‘Skip’s Song’) on the Dreamland album.

Ray Charles’ ‘Leave My Woman Alone’ picks up the pace slightly, with pleasingly discordant and ramshackle guitar work from Kesley as Plant gives out a hint of a jig, a move he builds on for a better-than-the- original run at Donovan’s ‘Season Of The Witch’ wherein he gets his maracas out – steady! – and prowls about the stage.

Worley now caresses a Puerto Rican cuatro – this is a best guess based on the number of strings on the instrument – for another Patty Griffin song, ‘Ohio’. Behind him, Jefferson is playing his drums with orchestral mallets as the voices meld together, rising with the melody. The band of course get a standing ovation that continues until they return to the stage after a brief break for Low’s ‘Everybody’s Song’ – Worley has gone off to Mali with his cuatro – and they gather around a microphone and one acoustic guitar to close harmonise a finish with “And We Bid You Goodnight” This traditional lowering funeral hymn has turned up in the work of both The Incredible String Band and The Grateful Dead, names I would suspect are dear to Plant’s heart. The closing adulation the band receive is as heartfelt as it is deserved.

I wouldn’t be surprised to find in the library of Plant’s no doubt stately home copies of Rob Young’s Electric Eden: Unearthing Britain’s Visionary Music and The Old, Weird America, Greil Marcus’ examination of American folk music by way of Dylan’s Basement Tapes. He has become some sort of living embodiment of the explorations made by both authors into the music of the past and how its vitality is still with us. And that’s not even to mention Plant’s connection with the music of other places. I could be here all week singing the praises of his African/Eastern tinged work with The Sensational Space Shifters. I have watched Plant live in many incarnations but I’ve never heard his voice sounding as comfortable as it did tonight, at home in the family he has created with these master musicians. In many ways he was only the backing vocalist – and he almost admitted as much himself – for Dian’s almost other-worldly presence. This is not a rampant superstar ego, but a musical seeker who simply wishes to serve the song. Almost entirely alone amongst his peers, Plant’s questing seems far from over. This is an artist to be treasured. We should be glad he refuses to make that telephone call.