Barrie and Tony Drewitt-Barlow want to help couples in similar circumstances to their own by sharing their surrogacy expertise.
Tony, 47, told Best magazine: "It's about helping people who can't normally have kids.
"I hope in 40 years time, whether you're gay or straight, it won't matter. If we can help same-sex parents become mainstream then our job is done."
The couple hit the headlines 12 years ago when they used a surrogate mother and an egg donor to father twins Aspen and Saffron (photographed above at their christening in 2000). They now have five children.
The couple sold their clinical testing business in 1998 and found themselves swamped by same-sex couples seeking advice.
So with Tony's clinical expertise, they set up the British Surrogacy Centre in Maldon, Essex, in February 2011.
However, according to COTS - Childlessness Overcome Through Surrogacy: "Membership fees contribute to the administration and day to day running costs of COTS. These fees would need to be higher were it not for the generosity of our members who have given or continue to give donations."
The Drewitt-Barlows were the first British homosexual couple to be named on their children's birth certificates.
The pair first hit the headlines in 1999 when they became the first British same-sex couple to be named on their children's birth certificates. The twins were born to a surrogate mother in California.
Following a ruling by an American court, they became the first British children to be registered as having two fathers and no mother.
Four years later, they used the same egg donor and a different surrogate to have another child. In 2010, the couple welcomed their fourth and fifth children into the world.
Twin boys Dallas and Jasper were born to the same surrogate mother who carried Orlando. The couple entered into a civil partnership in 2006.
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