Dolores O’Riordan, the lead singer of the Cranberries, drowned in a bath as a result of intoxication from alcohol, an inquest has found.

The inquest at inner west London coroner’s court, held on what would have been O'Riordan's 47th birthday, heard that she had been drinking heavily before she was found dead in room 2005 of the Hilton hotel in Park Lane, London, at about 9am on 15 January.

Her alcohol level was 330mg per 100ml of blood, more than four times the legal limit for driving. The court heard that she had struggled for many years with bipolar disorder and excessive drinking.

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O’Riordan, who had been in London for a recording session, was found by a maid the morning after she checked into the hotel. She was submerged face up in the bath, wearing a long-sleeved vest and pyjama bottoms. When paramedics arrived, police were performing CPR on her in the bathroom. At 9.16am she was declared dead.

Evidence was found of heavy drinking and smoking and use of prescription drugs including lorazepam. Five empty miniatures from the minibar, which had been accessed at 2.10am, were discovered as well as a 35cl bottle of champagne.

A postmortem report by Dr Adam Combe concluded that O’Riordan drowned as a result of alcohol intoxication. Levels of medication in her blood were therapeutic, no note was found and police said after her death that it was not suspicious.

The coroner, Dr Shirley Radcliffe, said: “There’s no evidence that this was anything other than an accident. There was no intention, this seems to be solely a tragic accident.”

The inquest heard that the Irish singer’s bipolar disorder had responded well to treatment. She went through periods of abstention from alcohol but there were also bouts of excessive drinking.

O’Riordan had previously discussed being sexually abused as a child by a family friend and how she suffered from anorexia.

In September last year she began composing a suicide note while drinking heavily and taking lorazepam, but evidence from Robert Hirschfield, a US psychiatrist who assessed her over the phone on 26 December, suggested she had been doing better.

In his statement read at the inquest, Hirschfield said: “She was doing well, she was not drinking, she was a little sad on Christmas Day … no thoughts of suicide.”

Another psychiatrist, Dr Seamus O Ceallaigh, said he spoke to O’Riordan on 9 January and she was in “good spirits”.

O’Riordan’s mother, Eileen, whom she called from her hotel room at 3am on the night of her death, attended the inquest, as well as one of the singer’s brothers, PJ, and a sister-in-law.

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In a statement released after the hearing, her bandmates thanked fans for their messages and support. “We continue to struggle to come to terms with what happened,” they said. "Our heartfelt condolences go out to Dolores' children and her family and our thoughts are with them today. Dolores will live on eternally in her music.”

The inquest heard that O’Riordan had a legion of fans who valued her charisma, unique singing voice and feisty on-stage performances. She was described as a loving daughter, fun-loving sister and dedicated and doting mother.

O’Riordan, born in Limerick in 1971, joined the Cranberries – then called the Cranberry Saw Us – in 1990 and performed with them until 2003, when they took a hiatus. They reformed in 2009.

Their hits included Linger, which reached the top 10 in the US and Ireland and No 14 in the UK. At the time of O’Riordan’s death she was in London to record a cover of Zombie, another of the Cranberries’ biggest hits, with the rock band Bad Wolves.

The Irish president, Michael D Higgins, was among those who paid tribute to O'Riordan after her death. She is survived by her three children, Taylor Baxter, Molly Leigh and Dakota Rain, from her 20-year marriage to Don Burton, Duran Duran's tour manager. The couple split up in 2014.