It can’t be every day that a group of teenagers climb on to a Cowley rooftop and sing classical music. But that’s what sisters Kate, Helen, Emma, and Laura Ashby, plus their brother Nick, decided to do as youngsters.

“As we are all very close together in age, singing became a real group hobby, and it was something we could share together,” Kate explains. “When we were teenagers we had our loft converted, and we were able to climb up on to the flat roof. We used to watch the sunset and do some singing, it was wonderful.”

Friends joined them too, and in due course the group blossomed out from its Oxford rooftop origins, and turned professional: now named Stile Antico, it has acquired an international reputation.

“The group is on tour in the States at the moment,” Kate adds, “But I’m heavily pregnant, so not allowed to fly, and be with them.”

Laura Ashby laughs as she describes herself as the “black sheep” of the family –— she isn’t a professional singer. Instead she plays as an amateur in a pop band, and has gone into music administration as a career — she works with Music at Oxford, and the Oxford Lieder Festival among others. Music certainly seems to be in the family blood.

“Our mum is musical,” Laura tells me. “Her mum was an opera singer, and her dad was a repetiteur and pianist for an opera company. Our dad is interested, but isn’t a musician himself. We were definitely brought up to be a musical family. The four girls are the eldest — the poor boy has four elder sisters — and we formed a string quartet. Our teenage rebellion was to go more towards singing than string playing. We all joined the local Hildegard girls’ choir when we were about ten, and that specialised in early music.”

All of which led to a decision to set up a new Oxford Early Music Festival.

Kate said: “We felt there was a gap in the market. The city has everything required for an early music festival, including perfect venues, and since we’ve been making music in Oxford since we were children, we know how many people are really interested in making music here. Also, last year Stile Antico was approached by the BBC to put on a concert in Oxford — there was a gap in their live broadcasting schedule. So we staged a concert in Merton College Chapel, and that gave us a further impetus to start the festival.”

The first festival consists of four concerts, staged from May 4-6.

Kate added: “I think having James Bowman coming to sing in Bach’s B minor Mass is really great, because we’ve got a lot of young groups in the festival, and to have an established talent like that coming back to Oxford is brilliant. We know that the groups who are playing and singing in the Mass are incredibly talented, but lots of people won’t be too familiar with their names. So having someone well known will hopefully encourage audiences to come and listen to the younger artists.”

Various city venues. (Details at oemf.co.uk) May 4-6 Tickets: 01865 305305 or ticketsoxford.com