The new statue of Princess Diana in the gardens of Kensington Palace has been savaged by art critics as “spiritless” and “calculated to appeal to the lowest common denominator” but is drawing large crowds.

Perhaps the critics have been unkind, for the statue’s design was approved by Diana’s sons William and Harry who were only 15 and 12 when they were made to walk heads bowed behind her coffin in 1997.

Diana was 36 and divorced from Prince Charles when she was killed in a car crash in Paris.

The princes, now 39 and 36 with children of their own, came together on Thursday, on what would have been their mother’s 60th birthday, to unveil the statue at a seminal moment for Britain’s very disunited royal family.

It’s hoped the act of coming together to remember their mother will help heal the rift between the brothers, caused partly by Harry’s claim that the royal family has behaved in a racist manner towards his mixed-race wife, the erstwhile American actress Meghan Markle.

Diana is shown with two boys and a girl to reflect her love of children. The princes have thanked the 69-year-old sculptor, Ian Rank-Broadley, who has a record of creating images of the royal family, and also the landscape artist, Pip Morrison.

But the critics are not impressed. The Guardian’s Jonathan Jones, for example, laments the statue’s “aesthetic awfulness” and says that Rank-Broadley’s sculpture is “a spiritless and characterless hunk of nonsense” that is ultimately “nauseating”.

The illusion to the Virgin Mary “shamelessly plays up to the most mawkish aspects of Diana worship”, writes Jones, with the “People’s Princess” portrayed as a “modern Mary”.

Rachel Campbell-Johnston, in The Times, agrees, adding that aesthetically the statue is “so horrible” it can only have been “calculated to appeal to the lowest common denominator”.

The outfit is “somewhat frumpy”, she says. Diana was renowned for her style, and it seems odd to memorialise her in such a way, the belt an already outdated faux pas, the skirt un-noteworthy.

As Campbell-Johnston says: “Could it be that Laura Ashley (a middle market fashion house) has made it on to a public monument?”

Diana stands “arms outspread in the pose of a traditional religious Madonna”, with her hands on the shoulders of two young children with a third hidden just behind.

In Campbell-Johnston’s opinion, the sculptor chosen to carry out this prestigious work should “certainly have been female”, not one of Britain’s “most safely established middle-aged white male artists”.

“Princess Diana deserved something much better,” she says.

Despite this mauling, large crowds of crazed Diana fans gathered on Sunday to experience London’s latest attraction.

At the unveiling, William and Harry put out a joint statement: “Every day, we wish she were still with us, and our hope is that this statue will be seen forever as a symbol of her life and her legacy.

“Today, on what would have been our Mother’s 60th birthday, we remember her love, strength and character — qualities that made her a force for good around the world, changing countless lives for the better.”

The day after the unveiling, Harry flew back to his new home in Hollywood.