Jacqui McShee feels lucky to be singing the blues.

With songs such as Born Under a Bad Sign and Been Down So Long (It Feels Like Up To Me) in the blues canon, good luck and the blues haven't often been regarded as going hand in hand. But the lower vocal range the former Pentangle singer has acquired as she's moved up in years, allowing her to be that bit more expressive, is, she says, some small compensation for reaching the stage in life when losing close friends becomes an increasingly regular experience.

McShee and her new group, Take Three, were particularly close to two of Scotland's great guitar heroes, Bert Jansch and John Martyn. Jansch and McShee kept the Pentangle name going for many years after the folk-jazz experimentalists' original line-up split in the early 1970s and her guitarist-bass player Alan Thomson and percussionist Gerry Conway both had long associations with Martyn (Conway also played drums with Jansch in a latter day version of Pentangle). So, all three have been left with huge gaps in their lives.

"I think about Bert every day," says McShee as she prepares for Take Three's first Scottish dates next week. "After the Pentangle reunion in 2008 I spent a lot of time up at Bert's place, listening to the recordings we'd made of all the gigs on the tour because we were going to release a live album. That's probably not going to happen now but Bert's death in a way freed me up to sing Black Waterside, which I always thought of as his song.

"I know it's a traditional song and anyone can sing them and do their own version. But I probably wouldn't have done that while Bert was still around and now Alan [Thomson] has done this wonderful arrangement, so it's a tribute to Bert while being a new venture for me."

The new group's name is not the first time the words "take three" have figured in McShee's career. Back in 1969 Pentangle were hired to provide the theme song and incidental music to Take Three Girls, BBC 1's first drama series to be filmed in colour, which focused on the lives of three young women making their way in a shared flat in swinging London. While the theme song, Light Flight, gave the band a surprise hit single, the huge success of the parent album, Basket of Light, arguably set them on course for the pressure and tensions that caused Pentangle to split up.

"We did two series of the programme and it was just something different for us," says McShee. "What followed soon after with the band wasn't nice but Take Three Girls was actually a lot of fun. It wasn't the sort of pressure situation it might have appeared to be. The producer would say to us, 'Do five seconds of this' and we'd launch into five seconds of something we already had in the pipeline while one of the girls went off to the loo then came out again. It was lavatory chain pulling music really."

The Pentangle reunion in 2008, as well as being a return to the musical form of their heyday, was also a return to the more easy-going personal relationships they'd enjoyed before the madness of the album-tour-album-tour scheduling that was rife in the 1970s and caused friction between the five members.

"We actually spent more time reminiscing than we did rehearsing when we started preparing for that tour," says McShee. "All the aggro and egos had gone because we were all a bit too long in the tooth for that kind of thing. We'd all grown up and we were enjoying each other's company like we did in the early days. And best of all, the music actually sounded a lot better than we'd dared to hope. There was some really good stuff on those recordings Bert and I were going through before he died."

As well as traditional songs that McShee has long known but never sung, Take Three features some of the jazz standards she grew up listening to, although the recent trend for singers including Rod Stewart and Paul McCartney to release standards albums dissuaded her from following suit.

"Maybe the next album we record will be more of a standards album," she says. "We've gone into some of the lesser-known ones for our first album and there are so many to choose from, I suppose, but I wanted to mix the jazz songs with folk and blues.

"I'm nearly 70 and I can't reach all the high notes I used to sing. But I can sing more lower ones now instead and I'm enjoying what we're doing. Gerry plays percussion, so he doesn't have to lug his drum kit, and Alan's playing acoustic guitar, so it's a more compact band – we can all get into the same vehicle."

Jacqui McShee's Take Three play the Fraser Centre, Milngavie, on April 11 and the Green Hotel, Kinross, on April 14.