Having married when she was 21 years old, the Queen beats any other monarch in having the longest marriage.
Catherine Butcher, co-author of 'The Servant Queen', a book on the Queen's Christian faith, told Premier about their marriage.
She said: "The Queen did pay public tribute to Prince Phillip in 2012.
"She said he'd been her constant strength and guide throughout their married life".
"Publicly, she made a statement but people of that generation tend not to say anything in public about relationships, but she did say that."
Commending the sacrifices Prince Phillip has made for the marriage, Butcher said: "He's someone who has given up his own career to serve her and he's shown that duty and faithfulness for 70 years which is something to be commended."
Speaking of the initial get-together, she commented: "It wasn't a match that was approved apparently; she fell in love with him as a young woman.
"Love wasn't really part of the equation often in royal matches so it was her act of rebellion."
Through 70 years, Butcher said the couple have had to persevere and also cope with the divorce of three of their children and the changing role of the royal family in the public eye.
When asked about Philip's faith, Butcher said during her research she was told that he was a regular church attendee.
She added: "I was told categorically that he turns up quite regularly - when she [the Queen] is here and not here, this is a regular part of his life, attending worship in a church at Sandringham."