It's difficult to be specific about the van’s colour. It could be pale mauve, or perhaps dark puce. Either way, it’s a great colour, because you can see it easily in traffic. Not that there’s any traffic out here on the road south from Ullapool, on a Sunday morning, but the principle applies, and now the van roars like a hallucinogenic rocket past the coffee shop where we’re attempting breakfast.

Never even saw us! Once Ivan’s behind the wheel, he’ll stop for nothing. Frazerburgh’s still some 150 miles drive. We’re supposed to be there by two o’clock. Ivan’s going to make it.

We finish our coffee and climb stiffly back into Tim Goulding’s car. Just Joe Thoma, the famous fiddler, and myself. Our new rhythm section – Niall and Dan Sweeney – are travelling in the van with Ivan.

“Do you think he saw us?” Tim asks.

“Ivan?” Joe laughs. “No way. He’s up behind the wheel, the boy. Eyes streaming in the cosmic wind, looking over his glasses at the road or peering at the map like a short-sighted owl. He’s very intent when he’s driving. God help the boys!”

I’d glimpsed their faces through the van’s wind shield, pale and tired above dark leather jackets. This is our third gig in 38 hours, and the strain’s beginning to tell. Packing the gear at two this morning in Ullapool, the old question came back. Why do we do this to ourselves? Because we’re Doctor Strangely Strange, that’s why, and we haven’t toured for 25 years. When we were invited to become part of the prestigious Highlands and Islands Festival, it was impossible to say no even though the money was derisory. Money’s not everything.

It works like this. Ivan Pawle – founder member along with myself and Goulding – also owns and drives the van. Take Tim’s car as well, and our transportation’s solved. The van takes the gear and PA, and the rest of us travel in the car.

The first gig was in Nairn, on the coast near Inverness. Not many turned up, but it was a live rehearsal, and allowed us surmount a few sound problems. Next night was Ullapool, a beautiful fishing town on the west coast of Scotland. A long neck of sea like a Norwegian fjørd, bare mountains and white buildings.

We played to a packed audience of German bikers, Australian back packers, and bemused locals. Started quietly, but soon got into gear and roared through the second set, to the amazement of the Germans, who, though professing a penchant for Status Quo, greeted Ivan’s guitar solos with synchronised Teutonic bliss. We’ve been asked back. Now it’s a 200-mile drive to Fraserburgh, jewel of the north-east . . .

Well, that’s over, and we’re on the road again to Aberdeen, where we play The Moorings Bar tonight. It’s got to be better than the Mariner’s, Fraserburgh. Anything would be! The bar was tiny, barely room to set up, and the audience – those who could remember their names – were straight from central casting. “Can ya play Mustange Saly, biyz?” There’s always one. I chanced a song about Phil Lynott from our current Alternative Medicine album (available from your usual outlets), and that got their attention.

The only people who really liked us – apart from the owner who liked us well enough to generously pay cash – were lunched-out old hippies and an off-duty cop. Said he’d be back later to bust the entire audience on the grounds of their inability to appreciate “goo’ musik”. He wasn’t joking.

We’re in Chris Simmons’ flat now, and it’s late. The Moorings gig, though poorly attended, went well, and Ivan met both his fans, and signed albums for them. United in bliss, he smiled the night away, while we packed the van and had a few drinks with the sympathetic bar staff.

Chris Simmons looks like something from the Furry Phreaks – Lynyrd Skynyrd t-shirt and strange shorts. He’s organising the tour, so we’ve got to be nice to him. It’s not hard. He’s on the ball. We talk into the small hours. Tomorrow we’re back at base in Sterling, and the next day’s free, so we’ll rehearse. There are still a few rough edges, and Dan (bass) and Niall (drums) need to reinforce the arrangements.

We do a two-hour set of originals, and it’s a lot to learn in a week. But it takes nothing out of them, they’re shit hot. They weren’t even born when we cut our first album, and we’ll probably be senile when they cut their last. Dan maintains that we’re gaga already. Either that or our pacemakers have been affected by the strobe lights.

Wednesday night, it’s Traaquair. A village hall 30 miles south of Edinburgh, a well-organised and well-attended gig. Davy McFarlane is with us on harmonica, and shifts the show up several notches. He normally plays in an R’n’B band called The Young Wolves. Check them out. The organisers had cooked us a wonderful meal (thanks Ishy), and after the gig it’s back to their house for something called The Glenfiddich – some sort of whisky, apparently – so it’s another late one.

Thursday morning, and I’m in the van with Ivan, and we’re motoring at speed, some 200 miles through beautiful scenery to Inverness, where we play the Festival Club tonight; it we get there before six, there’s a free meal, and on our budget, that could be a vital lifeline.

We eat, sound-check, meet the Festival’s remarkable organisers, and play to a reasonable audience, but feel that we don’t get much feedback from the crowd. Davy says audiences are like that up here. Chris has recorded the gig from the desk, but at four in the morning, nobody in the band wants to hear the tape. Tomorrow, we have to be in Aberdeen by 11am to do a live gig for BBC Radio Scotland in a place called The Lemon Tree. It’s over a hundred miles of bad road there, so we’re leaving at eight. That’s only four hours away, and we’re still not in bed.

Plockton is like something from a tourist board’s wet dream, an idyllic small harbour on the edge of the west coast, surrounded by rhododendrons and severe mountains. It’s only negative being that it’s nearly 200 miles from Aberdeen, which we left at four in the afternoon, and the last 30 miles of road are single lane. You have to pull into passing areas to allow oncoming traffic get by.

We arrive at half past nine, and don’t go on till midnight, so there’s a little time to relax and chill out. After The Lemon Tree gig this morning, we need that. Even though we use electronic tuners for the guitars, tiredness had overwhelmed us on one number, and we had to abandon it. However, the producers didn’t seem too phased, and said they’d enough to make the programme, and that the interview had gone extremely well. Fingers crossed.

There’s a group from the Orkneys on before us, Ivan Drever, Duncan Chisholm and Mark Duff. They make beautiful, fragile music. Their fiddler Duncan heard us last night in the Festival Club, and has kindly offered to lend Joe Thoma a solid fiddle, because this is another village hall gig, and we’ll need to play with a bit of welly to get the crowd going, and it’s crowded in here, full of great bearded Highlanders, puzzled Swedish tourists, and strange Danish women who look as if they’ve stumbled out from the pages of some bizarre corporate power-dressing catalogue.

The gig goes like a dream. We run out of material after a couple of hours, but Dan steps to the mike in true style and sings a medley of rock ’n’ roll in the key of A, playing bass the while, to all our great pleasure. The boy’s going to be a star.

Ivan knows the licks, and, sounding like a very loud garage band, we drive the audience into a frenzy of previously unseen dance steps. Later on, the boys back a few local girls who fancy themselves as singers, and Goulding lays down keyboards on a bizarre ‘Wonderwall’. We’ll never let him live it down. Tomorrow it’s back to Aberdeen to play The Blue Lamp. We’ve got all day this time, and plan to get up late – say about half-eight.

The drive is amazing. Nobody lives in the Highlands except for a few nobs and the remains of a once-plentiful crofting community. The Clearances fixed that, when the capitalistic landowners drove out the indigenous locals to make room for more sheep. Same old same old. 600 people own the whole of Scotland. No wonder the Scots want their own government.

The Blue Lamp’s the sort of venue Dublin badly needs. Well-run, holds maybe 400 max, an in-house PA and a sense that the audience come here for the music – and if anything else should be on offer, that’s a bonus. Every reasonably sized town in Ireland should have a gig like this.

We play good, and sell lots of CDs, mainly to musicians, which is a great compliment. Davy couldn’t be with us tonight, so a harp player called Spider gets up for the last couple of numbers, occasioning Dan to go into his Young Elvis routine again. We’re tight, now, and back in Chris’ place, we listen to that tape from Inverness. It’s not half bad, he says, which actually means that it’s slightly more than half good. Tomorrow’s our last night. It’s always like that. The act knits together just as the tour ends.

The Tolbooth Art Centre in Stirling’s a wonderful space, and the venue and sound are perfect, but despite publicity, the gig is poorly attended. We don’t mind. We may know that the audience outnumbers us, but we can’t see them for stage lighting. Afterwards, it was back to Davy’s place for more of the same.

So what do we think, now that we’ve finally made the ferry from Stranraer? We have to do this again, that’s what, only next time we’ll preplan a bit more, and get the itinerary into some kind of shape. 2,500 miles in ten days is pushing it a bit, but as Thoma says:

“I’ll tell you something boys, I enjoyed 95% of that, and 75% of it . . . I enjoyed hugely!”

Our audiences seem to have felt the same way, which – for old men like us, these days – is as good as it gets.

• Alternative Medicine by Dr. Strangely Strange is out now on Ace Records.