The star was honoured for her multi-million selling album, 25, which emerged last year after a long struggle with writer's block.

She was unable to accept the award in person, having played in Zurich, Switzerland, on Wednesday night.

But in a video message, she said he was "very grateful."

"I won it on my last album as well... but I was secretly pregnant, so I didn't enjoy the night too well," she added.

"To win it this time is truly, truly humbling."

Damon Albarn won the lifetime achievement award, in recognition of an eclectic body of work that spans rock, pop, rap, world music and opera.

Presenting the award his Blur bandmate, Graham Coxon, said Albarn had already "fitted in two lifetimes of work... so far".

The star then delivered one of the most well-received speeches of the day.

"What is songwriting? What is it all about?" he said. "True songwriters are people who are able to release themselves from something that's really affected them by writing a song about it.

"Some of us see it as going to church, some of us see it as going to work, but at the end of the day, if you're not connected to the spirit you're not making true music.

"Thank you for this extraordinary, life-affirming honour."

'Been amazing'

Other awards went to Portishead, Bryan Adams and Irish indie-folk band The Villagers, whose album Darling Arithmetic won album of the year.

Frontman Conor O'Brien, said the album was particularly important to him, as "a month after it came out, I finally got to experience what it feels like to be an equal citizen in my country when the Irish people voted yes to marriage equality".

"The songs took on a whole new life to me from that moment on. Touring these songs has been a really cathartic experience for me. So many people have told me their stories. It's been amazing."

The award for best song musically and lyrically went to Wasn't Expecting That by Jamie Lawson.

The newcomer beat Wolf Alice and Ed Sheeran, who signed Lawson to his record label. In his speech, Lawson said he would be "forever grateful" to the "ginger kitten" for giving him a career.

The classical award went to Oliver Knussen, who wrote and conducted his first symphony at the age of 15 and has been a champion of new music ever since.

The composer's outstanding body of work includes Two Organa, Ophelia Dances, Flourish with Fireworks, an opera based on the children's book Where The Wild Things Are and the deeply personal Requiem: Songs for Sue, written for his wife, who died in 2003.

Accepting the award, Knussen warned the government to keep its "hands off the BBC" - but he also warned the corporation not to sideline difficult or challenging new works.

"Don't relegate all of us to a two-hour slot that you seem to regard as a place to put pond life," he said.

"Some of it is a bit prickly. But some very nice things are prickly... or so I'm told."

British hitmaker Wayne Hector won the international achievement award in recognition of two decades of chart success.

The British writer achieved his first number one in 1996, with Peter Andre's Flava. Since then, he has penned singles for the likes of Britney Spears, Nicki Minaj, One Direction, Sigma, Westlife and Pussycat Dolls.

"I'm fiercely proud to be British," he said. "We have the most amazing musical heritage in the world."

Simple Minds won outstanding song vollection, while Madchester band Happy Mondays took home the inspiration prize. 

"After 30 years, to finally be recognised for writing a song - it feels great," frontman Shaun Ryder told the BBC.

The Ivor Novello awards are voted for by songwriters, with judges this year including Alison Moyet, Sharleen Spiteri, Wretch 32, Cathy Dennis, Joan Armatrading, Guy Chambers and Charlotte Church.

Now in its 61st year, it has honoured the work of more than 750 songwriters and composers, including the Beatles, Kate Bush and Sir Elton John.

Full list of nominees and winners

Best song musically and lyrically

Wasn't Expecting That - Jamie Lawson

Bloodstream - Ed Sheeran

Bros - Wolf Alice

Best contemporary song

All My Friends - Snakehips ft Tinashe & Chance The Rapper

Cargo - Roots Manuva

Shutdown - Skepta

Most performed work

Hold Back The River - James Bay

Hold My Hand - Jess Glynne

King - Years & Years

Best album

Darling Arithmetic - Villagers

In Colour - Jamie xx

Matador - Gaz Coombes

Best film score

Ex Machina

Pan

The Duke of Burgundy

Best television soundtrack

London Spy

And Then There Were None

From Darkness

Lifetime achievement: Damon Albarn

Outstanding song collection: Simple Minds

PRS for Music outstanding contribution to British music: Portishead

PRS for Music special international award: Bryan Adams

Songwriter of the year: Adele

The Ivors classical music award: Oliver Knussen

The Ivors inspiration award: Happy Mondays

(BBC)