Their experiences are way different – they’re certainly new to my ears, at least.”Just as in the Dead, Weir provides the loosest of structures, so that the music can grow organically and offer constant surprises – to musicians and audiences alike. So how do Ratdog fit into the grander scheme of things? “This band is essential to The Dead; we’re The Dead’s test monkeys,” Weir asserts. That tour, for example, included Dead staples such as “Playing in the Band”, “Terrapin Station” and acid rock’s Holy Grail, “Dark Star”, as well as covers, such as a jam taking in The Beatles’ “Tomorrow Never Knows” and “Mathilda Mother” by the Syd-era Pink Floyd, the perfect Haight-Ashbury nod to psychedelic Swinging-Sixties London.If that modus operandi sounds familiar, it is, after all, what you’d expect from a founding member of the Grateful Dead. On last year’s European tour, even hardened Deadheads were surprised at how good the band were: tight, confident and sharp as a pin, they could move seamlessly from Dylan tunes to old country blues to extended jazzy explorations that reached far into “the zone”, a magical place where all six musicians are indispensable components of an awesome improvisatory unit. But, basically, we do what we’ve always done – just go out there and play.”And play Ratdog certainly can. We’re working up all kinds of stuff – Ratdog songs, old Dead tunes and new approaches to material, particularly seeing how we can use this technology to arrive at fresh structures. He has been testing out the musical possibilities of looping, digital technology that allows him to build up multiple layers of his own voice, on top of which he can improvise scat vocals.”Basically, it’s a new instrument,” he says “And it’s turning out to be a lot of fun.

But he does a lot of stuff that doesn’t work as well in the format of a rock’n'roll band.”Then there is the new trick Weir has up his sleeve. For one thing, Rob Wasserman, a masterful acoustic bassist, has left to pursue his own projects. His replacement is the English-born Robin Sylvester, an injection of new blood that clearly excites Weir. “Robin is the right player for this band, and he’s fitting in just perfectly,” Weir says in his laid-back, northern-Californian drawl.

“Rob Wasserman used to be my whole band when we started out as a duo in the early Nineties, and he fulfilled that role admirably. Long derided by some Deadheads for his “pop” sensibilities, he has, ironically, given the Dead some of their most cherished jamming vehicles, such as “Playing in the Band”, “Weather Report Suite” and “Estimated Prophet”.The Ratdog that visits Britain this month is a subtly different beast. First taught by Jorma Kaukonen, Jefferson Airplane’s guitarist, and then apprenticed to Garcia as they played in the various groups that preceded the establishment of the Grateful Dead in 1965, Weir has a unique style full of odd time signatures and progressions that no other player outside of hard bop could contemplate. For fans this side of the Atlantic, it affords an opportunity denied to their vastly more numerous cohorts in the US: the chance to see, in a series of intimate venues, a man who is arguably rock’s greatest, if most eccentric, rhythm guitarist.Weir has come a long way since his early days in the Dead, when, as the 16-year-old kid with long hair and androgynous teenage good looks, he was the most mischievous member of that band of merry pranksters. Now a bearded 55-year-old, he possesses a unique style forged out of the need to establish a personal voice between the extremes of Garcia’s wildly inventive guitar-lines and the equally probing playing of Phil Lesh, a bassist who, in effect, uses his instrument as a lead all of its own. As their sell-out summer US tour this year shows, the band have lost none of their huge pulling-power.For Weir, a key to keeping the light aflame has been his offshoot band, Ratdog, who, following a low-key but ecstatically received European tour last year, return to Britain for a five-date visit, kicking off with a gig at the London Astoria tonight.

The death, in August 1995, of the lead guitarist Jerry Garcia brought that amazing journey to what seemed a natural end. But such was the power of what they had created that the remaining musicians, in one way or another, kept the creative spirit of the Dead alive in side-projects. It prompted their decision, last autumn, to reform under the abbreviated moniker The Dead – a recognition that, without the presence of the affable genius of Garcia, they could never be quite the same band. As a founding member of the Grateful Dead, that quintessential Sixties band, he was a key component of a 30-year trip into the outer galaxies of collective improvisation. The reappearance of long-lost American rock’n'roll heroes is becoming something of a regular phenomenon. In the past couple of years, we’ve had Brian Wilson re-emerge from years of self-imposed exile, and even Arthur Lee – long written off as beyond help – has triumphantly revisited the Love canon.
But Bob Weir is different For a start, he’s never been away.