NICK Cave's wife Susie has shared a poignant tribute to her late son Arthur on what would have been his 20th birthday.

Arthur, whose twin Earl celebrated his birthday with his family, fell off a cliff near their Brighton home after taking LSD in 2015.

The actress-turned-fashion designer, 53, took to Instagram to share photos of the bittersweet festivities on Tuesday.

Susie hung up a pink heart-shaped balloon in Arthur's honour at the party.

She captioned the touching snap: "A birthday heart for our little Arthur."

She wrote: "HAPPY BIRTHDAY DARLING EARLY."

Nick and Susie Bick married in 1999 and welcomed sons Arthur and Earl the following year.

Arthur (pictured below) was just 15 when fell to his death after "reaking out" during an LSD session with a friend.

The teenager stumbled off a 60ft cliff into the sheer Ovingdean Gap in July 2015.

The Argus:

Nick's most recent album Ghosteen, released in October, was written in the aftermath of the tragedy and explores the singer's grief.

Earl is now an actor who has starred in Channel 4 mini series Born to Kill, Netflix's The End of the F**king World and the new Alex Rider series.

Susie, who used to be a model, revealed she has now learned to value the "'happy moments", after having therapy to help with the grief following the death of her son.

In an interview with The Telegraph, she also described how she found that she "loved being a mother more than anything" when bringing up her twins.

The Argus:

Susie detailed how the strength of her relationship with Nick has helped her following the loss of Arthur.

"We’re together all the time except when Nick’s on tour – and then we speak about four times a day. I swear we never argue," she said.

"He’s a very easy person to get on with: wonderful, generous, kind.

"If one of us isn’t feeling so good, we’ll prop up the other.

"We really don’t want the other one to fall."

She said that therapy has also helped, explaining how she has to do things "that make me physically strong".