Sir Keir Starmer has said it is "easy to sit here and criticise" the Duke and Duchess of Cambridge's tour of the Caribbean, after parts were described as a "disaster".
The Labour leader added Prince William "could have gone further" after the heir to the throne chose not to apologise for Britain's role in the Transatlantic slave trade, instead saying the atrocity "forever stains our history".
The Duke and Duchess spent eight days touring Jamaica, Belize and the Bahamas in what is widely regarded to have been a PR disaster.
William is said to have had a meeting with aides following a backlash sparked by a number of gaffes, including accusations the couple were “tone deaf” after they were seen shaking hands with crowds behind a wire mesh fence in Kingston.
Images of the pair riding in the back of a Land Rover were denounced as harking back to colonial days, while there were protests aimed at the royals and how they have historically benefitted from the “blood, tears and sweat” of slaves.
Media coverage of the tour has been split, with some emphasising the positive impact of their presence in the Caribbean, while others described the fence photograph as a “PR disaster”.
William is understood to have undergone "crisis talks" with senior aides over the trip, which came to a close after he and Kate boarded a flight back to the UK.
Just before boarding their flight, the duke released an unprecedented statement addressing the growing republican sentiment in Jamaica, Belize and the Bahamas, acknowledging it had brought into even "sharper focus questions about the past and the future".
It comes after Barbados replaced the Queen as head of state in November, and elected its first president during a ceremony witnessed by the Prince of Wales.
Speaking on LBC's Call Keir, Starmer agreed William was trying to "cut his own groove" before becoming king, but admitted he "could have gone further" as William stopped short of issuing an apology over Britain's role in the Transatlantic slave trade.
Starmer said: "He could have gone further but again it's a difficult one and I think that he may go further in the future."
Asked if he thought the trip was a failure he said: "I don't think it was. William and Kate went on an important trip with important messages including messages about the changing Commonwealth going forward and that is difficult, it's very easy to sit here and criticise.
"Before I was a politician I was a lawyer and I did a lot of work in Commonwealth countries, including in the Caribbean and in Africa.
"I've been to Jamaica many, many times and I know just how strong the connection is between those countries and ours, it's very very deep.
Watch: Prince William suggests Commonwealth could be led by a non-royal
"But of course that relationship changes. I want it to endure, I want it continue and I think it will but in the end William and Kate are right - time changes things and we need to make sure the relationship is fit for the future as well as the past."
However, the couple were defending by a UK minister, who dismissed the criticism as “Twitter outrage”, according to the education secretary.
Asked whether William and Kate’s royal tour had an “unfortunate hark back to colonial times, Zahawi said: “No, I don’t believe that. I believe the tour has been a fantastic outreach for the prince and his wife. They have done a tremendous job.”
“I think we should be proud of the Commonwealth. I think Prince William was very wise to say, actually it is up to the Commonwealth countries if they feel they want him to be the head of the Commonwealth.
“I think that will strengthen the Commonwealth, not weaken it. And I think Prince Charles will make a great king, as will Prince William.”