A conservative Christian speaker at Sunday’s anti-marriage equality rally in Trafalgar Square said that the legalisation of same-sex marriage in the UK would lead to colonialism, and claimed men could only have faithful relationships with women.

Chris Sugden, the Executive Secretary of the Christian group Anglican Mainstream, appeared as a speaker at Sunday’s protest against marriage equality in Trafalgar Square.

In a speech to the crowd he argued that the legalisation of same-sex marriage would have “international implications”, as “it will require countries that are offended by it to have such ceremonies on their soil in our embassies and military bases.”

“It will require countries that are offended by it to change their laws and their culture in order to receive much needed aid for the poor and for victims of disasters,” Mr Sugden continued, concluding that: “This is colonialism again.”

He predicted marriage equality opponents in the UK would be prohibited from voicing their opinions in future: “We have all come together to proclaim that Real Marriage between a man and a woman ensures the future. We also know that in the not too distant future a rally like this may be illegal… Holding such [anti-same-sex marriage] views will be made illegal.”

Mr Sugden said workers in the UK would be “denied reasonable accomodation” for their anti-same-sex marriage beliefs in the workplace, citing the example of teachers who will “have to explain same-sex marriage to children.”

“We stand here for liberty,” he added. “Without liberty, the state takes over as parent, the state takes over as governor of your institutions, the state takes over as the regulator of all behaviour. We will all be nationalized.”

He went on to suggest that relationships between gay men are never monogamous, stating: “Only one creature has been known to calm men down into faithful and stable relationships since the dawn of time – a woman.”

Anglican Mainstream were part of a coalition of Christian groups which tried to run bus ads that read “Not Gay. Ex-Gay, Post-Gay and Proud. Get over it!” and were in response to a previous bus poster campaign by gay rights charity Stonewall, which said: “Some people are gay. Get over it!”

French anti-equality group La Manif Pour Tous was granted permission to hold the rally at Trafalgar Square to coincide with a large-scale anti-equal marriage protest at the Champs-Elysees in Paris.

 A much larger Manif Pour Tous event took place in Paris today, with an estimated 300,000 marching against same-sex marriage.