Scotland Yard appointed the head of its serious crimes branch Saturday to investigate a tabloid's publication of a private royal family photograph.

But a Conservative Party lawmaker criticized the appointment of such a high officer, saying it is like sending in commandos to nab a parking offender.Commander Roy Penrose, 46, former head of the drug squad, will lead an inquiry to discover how The Sun, a 4.15-million-circulation newspaper, obtained the snapshot of the queen, her mother Elizabeth, and the Duchess of York cradling her infant daughter Princess Beatrice.

The Conservative lawmaker, Geoffrey Dickens, protested the "Gilbert and Sullivan" situation in which Scotland Yard assigned Penrose to deal with "this piddling affair."

"We must presume that the Lord High Executioner is waiting in the wings to do his stuff when the hapless culprit is found. It is like sending in the SAS (commandos) to deal with a parking offender," he said.

After the picture appeared on the front page of Thursday's Sun, the queen told her lawyers to consider action against the paper.

Buckingham Palace said it was taken by an unidentified friend of the royal family and "was published without the permission of the queen or any member of the royal family or the person who took the photograph."

The Sun defied the queen by again publishing the photo in its first edition on Friday but withdrew it from later editions and offered to return it "when it is established who is the owner." The paper promised not to publish it again or reproduce it elsewhere.

In an editorial Saturday, The Sun said its "crime" was to publish "a delightful picture" that readers loved and that the queen should have been proud to share with her subjects.

The paper said it was "hurt" by the palace's reaction but apologized: "Sorry, Ma'am. No offense meant." The Sun gave no explanation of how the picture was obtained.

The appointment of Commander Penrose was announced in a one-sentence Scotland Yard statement.

Buckingham Palace refused to comment, saying only that it was advised that Scotland Yard was investigating the matter.

Dickens said he planned to ask Home Secretary Douglas Hurd, who is in charge of the police, to issue guidelines on the "sensible use of police resources."

Buckingham Palace has released only a few official photos of Princess Beatrice, the queen's fifth grandchild, who was born on Aug. 8. They were taken by the baby's father, Prince Andrew, the queen's second son.

Although posed, the photo which appeared in The Sun was informal and relaxed, showing the queen and her mother in Scottish tartans.

Under British law, copyright on a photograph lies with the photographer.

Television news programs, when reporting the controversy, have blacked out the picture when showing The Sun's front page.

The first recorded case of the royal family going to the courts was in 1911 when King George V brought a libel action against an anti-royalist who claimed in a Paris paper that the king married an admiral's daughter 20 years earlier.