The Victims’ Commissioner is demanding that the Metropolitan Police explain its decision not to pursue a full investigation into claims a teenager was trafficked to the UK to have sex with Prince Andrew.

The Observer understands that Dame Vera Baird QC, a former solicitor general and chair of the Board of the Association of Police and Crime Commissioners, has taken a close interest in the allegations, first examined by Scotland Yard in 2015.

Baird, who has focused on protecting victims of sexual and domestic abuse throughout her career, is currently observing election purdah and cannot speak to the media.

However, prior to the election she made her views known to a victims’ rights campaigner, telling him that she would be requesting a meeting with the Met once purdah was over.

“Before the election was called I spoke at length with the Victims’ Commissioner and we both find it extraordinary that this matter was not proceeded with,” Harry Fletcher said.

The Met has said that its investigators reviewed all “available evidence” after receiving a complaint relating to claims that were made in court documents. It was alleged that in 2001 a 17-year-old, now known to be Virginia Roberts, was “forced to have sex with Prince Andrew”, purportedly at the London home of socialite Ghislaine Maxwell, the one-time girlfriend of the late disgraced financier Jeffrey Epstein. His victims are now bringing claims for damages against his estate.

It is understood that lawyers for Roberts also independently contacted the force in 2016. But the Met chose not to pursue a full investigation.

Channel 4 News reported in August that “the Met Police has refused to answer detailed questions about the allegations and whether they ever spoke to Epstein, his friend Ghislaine Maxwell, Prince Andrew or anyone from the royal household”.

How seriously the Met took the claims is expected to form a key part of a BBC Panorama investigation into the Epstein scandal which will include an interview with Roberts and is due to be broadcast in December.

The Duke of York denies having sex with Roberts. In his Newsnight television interview he said he did not recall having ever met her.

But a photo of him with his arm around Roberts’s waist has been widely circulated. There are claims the photo is fake. The duke says he cannot remember a picture being taken when he was in Maxwell’s house.

It is believed that lawyers for Virginia Roberts Giuffre, above, contacted the Metropolitan police in 2016. Photograph: Bebeto Matthews/AP

“You would expect the Crown Prosecution Service to have provided pre-investigative advice in this matter,” said Fletcher, an adviser to Plaid Cymru and several victims’ charities. “It needs to be confirmed whether this happened.”

A spokeswoman for the CPS said its lawyers have “confirmed that we cannot comment on any input into investigations where persons have not been charged”.

In a statement the Met confirmed that it had received an allegation of “non-recent” trafficking for sexual exploitation. “Having closely examined the available evidence, the decision was made that this would not progress to a full investigation,” the Met said. Given the heightened interest in the case, the Met confirmed it had revisited the decision and concluded that it was the correct one. “Therefore no further action is being taken,” it said.

But speculation about what went on at Maxwell’s home is unlikely to die down. Lawyers bringing civil claims against the Epstein estate are looking to subpoena the duke, obliging him to provide testimony under oath as a witness. The duke has confirmed that he would be prepared to help law enforcement agencies but has given no commitment to cooperate with any civil actions.

The duke’s decision to step down from public duties last week came after a raft of companies and charities sought to distance themselves from him following his disastrous interview. It is thought that both the Queen and Prince Charles were instrumental in forcing the duke to stand down. Prince Charles is reportedly returning to the UK on Monday after a royal tour, when he is expected to hold crisis talks with his brother.