His birth index:

First name(s) ANTHONY G
Last name VINCENT
Birth year 1939
Birth quarter 4
Mother's last name Viner
District Amersham
County Buckinghamshire
Country England
Volume 3A
Page 2394
Record set England & Wales Births 1837-2006

His birth certificate adds:

Birth date & place: 9th Nov 1939 at St Joseph’s Nursing Home, Beaconsfield UD
Full name: Anthony Gustave Vincent
Father & job: George Gaston Vincent, public relations officer
Mother: Noel Christabel Vincent (note this was Christobel for her second son and Christabel at birth)
Informant: S Vincent, grandmother of, with the family, St Michaels Green, Beaconsfield
Registration: cert No 209, on 23rd Nov 1939
_______________

There are at least three possible marriages for him:

Last name First name Born Died Event Record set  Location

Vincent Anthony G — — 1959 England & Wales Marriages 1837-2008  Surrey South Western, Surrey
Vincent Anthony G — — 1962 England & Wales Marriages 1837-2008  Plymouth, Devon
Vincent Anthony G — — 1985 England & Wales Marriages 1837-2008  Bath, Somerset
Vincent Anthony George — — 1962 Devon Marriages  Plymouth, St Jude, Devon, England

The fourth is the church version of the second, adding only the precise marriage date.

I can think of no way to identify his marriage, if any, apart from purchasing all the marriage certificates, possibly starting with the Surrey one.  The certificates give both the fathers of the participants and their ages, to compare or correlate with the above birth data.
_____________

This death notice was found on a Canadian web site, from The Citizen of Ottawa, Ontaria, and is clearly for him:

“VINCENT, Anthony Gustave On Friday, Oct. 29, 1999, Anthony Vincent, in Royal Victoria Hospital, Montreal. Beloved husband of Lucie, and very dear father of Alexandra. Much loved brother of Nicholas and wife Ghislaine (with daughter Ariane) of Victoria, B. C. Amanda of Montreal, and Rory of Vancouver Island. Dearly loved son of Lady Noel Stratheden (Sussex, England) and the late George G. Vincent, and dear step-son of Jane Vincent-Havelka (London, Ont.). Anthony Vincent was Canadian Ambassador to Spain and Andorra. Previously he served as Ambassador to Peru (with Bolivia), and High Commissioner to Bangladesh (with Burma), and held postings in India, and the Netherlands. A private cremation in Montreal will be followed in due course by a Memorial Service in Ottawa. The family thanks the staff at Clinica La Luz in Madrid, Spain, and the Royal Victoria Hospital, Montreal, for their excellent care and support. We would welcome any personal memories of Anthony. Memorial donations to Canadian Heart Foundation or Kidney Foundation. Ottawa Citizen, Nov. 2/99”

It just happens to identify his father, mother, wife, daughter, brother.
_______________

If the above notice is true, it is likely that he did not marry in Britain, so any purchase of certificates would be a waste of money.  Further his wife is named as Lucie which is not the name of any of the British wives.

Further there is a mention of a brother Rory of Vancouver Island.  He is not in the British records so it is possible that the family emigrated to Canada before Rory’s birth.

Canadian records are not public until they have been dead a while, so it is going to be difficult to get confirmation of much of the content of this notice.
______________

A bit of confirmation from the Japanese Foreign Minitister of that time:

“Statement of Foreign Minister Yohei Kono on the Demise of Mr. Anthony G. Vincent, former Ambassador of Canada to Peru

“November 1, 1999

“On behalf of the Government of Japan, I extend my heartfelt condolences on the demise of Mr. Anthony G. Vincent, former Ambassador of Canada to Peru (incumbent Ambassador of Canada to Spain), to his widow, Mrs. Lucie Houle, their daughter, and other bereaved family. It was Mr. Vincent, who, when the Japanese Ambassador's Residence in Peru was seized and occupied, worked for a long time for the purpose of mediation toward a peaceful solution of the incident as a member of the Guarantors' Committee.

“From the initial seizure of the Residence, Ambassador Vincent risked his life in an extreme situation seeking a solution of the incident, through mediating between the Peruvian Government and the terrorists on a neutral footing, and visiting the hostages during their captivity to encourage them. The sincere attitude and personality of Ambassador Vincent, who made every effort to gain the release of the Japanese and other hostages, still remain vividly in the memories of the Japanese people. His achievements will have a permanent place in the histories of Japan, Canada and Peru.

“The Government of Japan reiterates its gratitude and respect for Ambassador Vincent's great courage and excellent achievements as a diplomat, and prays that his family will overcome their sorrow.”
________________

CBC News of Canada has this article:

“Prime Minister mourns death of Canadian diplomat
CBC News Posted: Nov 01, 1999 4:38 PM ET Last Updated: Nov 01, 1999 4:38 PM ET”

“Prime Minister Jean Chretien has paid tribute to former Canadian ambassador Anthony Vincent, who died of heart failure Friday in Montreal. He was 59.
Vincent was appointed Canadian ambassador to Spain in 1997. But he gained international prominence while he was Canada's representative to Peru.
Vincent was one of 700 people taken hostage at the Japanese Embassy in Lima in December, 1996. He was released a few days later after winning the confidence of the leftist rebels.
He was a key intermediary in the effort to resolve the crisis, which dragged on for nearly five months.
Chretien said Canadians will remember Vincent for the courage and perseverance he displayed during the hostage-taking.
"He was a most able public servant who earned the abiding respect of his colleagues. He will be sorely missed," Chretien said.
Foreign Affairs Minister Lloyd Axworthy praised Vincent for his outstanding contribution to Canada's place in the world.
"His distinguished service to Canadians will long be remembered. His consummate professionalism won him and this country respect at home and abroad," said Axworthy.”
________________