SCOTTISH rockers Fatherson are on the up and up - and are increasing in number.

The band has headlined the likes of The Arches and The Garage without even releasing an album.

Now the group is set to do that, having switched from being a trio to a full-time quartet, and sometimes a five-piece.

"It has been a natural progression, we never sat down and said, 'Let's be a four piece now or add a cello player'. It just happened," says bassist Marc Strain, ahead of the band playing next week's Stag And Dagger festival in Glasgow.

"As a three piece you need to be careful about the guitar parts or extra percussion, because you will be playing it live.

"Now we have gone mental with the guitar parts we are writing, and hope that will help with bigger and bigger shows-"

Even as a trio the group were doing well. Originally from Kilmarnock but now based in Glasgow, their brand of hard rock and snappy melodies earned them support slots with the likes of Feeder and Admiral Fallow.

Now the group, who comprise vocalist Ross Leighton, drummer Greg Walkinshaw, keyboardist Chris Beltran, cellist Elaine Glass and Marc, are hoping to release their debut album by the end of the summer.

"People think this is a quick thing but it takes time, although we will have a single out in the short-term," says Ross.

"We have been a band for ages in different forms, and the album was getting too heavy with older stuff, so we wanted to change things."

That means there should be some newer material on show at Stag & Dagger, with Fatherson slated to play at the O2 ABC on the night.

Venues taking part in the one ticket, multiple gigs experience include Stereo, Nice & Sleazys and the CCA, while acts appearing are We Were Promised Jetpacks, Rachel Sermanni and former Coral guitarist Bill Ryder-Jones, amongst many others.

Marc says: "Stag's got a good name, and there are lots of bands we know and are pals with, so it should be good fun."

As part of the festival, Fatherson will get to appear on the main ABC stage, continuing their recent streak of decent-sized venues to play in Scotland.

Yet they're also trying to expand further afield, and have recently been gigging in England.

"It would be easy to just keep gigging here," adds Marc. "People know who we are and will keep coming to the shows, but we want to have broader horizons.."

l Stag & Dagger, Saturday, May 18, £19, 3pm