She had failed to reappear after the concert with her school friend Eilidh MacLeod, 14, who was still unaccounted for last night.

Eilidh’s mother Marion had travelled with them from the Isle of Barra and was due to meet them outside the arena.

She mounted a frantic search of hotels and hospitals and was asked by police for detailed descriptions of the girls’ clothing in a bid to help locate them.

As her husband Roddy, and Laura’s parents, Michael and Nan, arranged to fly to Manchester, islanders in the close-knit community of around 1,000 feared the worst.

But Angus MacNeil, the SNP general election candidate and a close friend of the families, learned early on Tuesday night that one of the teenagers had been found.

He said he understood Laura was suffering from very serious burns, suggesting the pair may have been close to the blast, and added that the whole island was “still numb with shock” and extremely worried about Eilidh.

Cecilia MacFadyen, Laura's grandmother, said at her home on the island: "Laura is alive and in hospital. I don't know anything about Eilidh."