The founder of Christian Concern, who has previously blasted the “militant homosexual lobby”, will be debating the arrival of equal marriage in England and Wales at The Law Society in central London this evening.

Barrister and evangelical activist Andrea Minichiello Williams will be on the panel along with LGBT legal advocates Lucy Scott-Moncrieff, former president of The Law Society, and S Chelvan, one of the UK’s leading barristers specialising in LGBT asylum policy and casework.

Barrister Hafsah Masood and the Rev Benny Hazelhurst are also on the panel.

Christian Concern was founded by Ms Williams in 2008 to protect “Britain’s Judeo-Christian values”.

Along with unsuccessfully fighting the arrival of equal marriage, Christian Concern’s sister organisation, the Christian Legal Centre, supported efforts against Transport for London’s 2012 decision to ban gay conversion therapy adverts from being displayed on buses in the capital.

The High Court ruled in favour of TfL in March this year, stating that running the adverts could cause “great offence”.

Ms Williams described it as a “victory” for Christian freedom because the High Court criticised TfL in the way it took the decision.

Justice Lang ruled that TfL’s process in introducing the ban “was procedurally unfair, in breach of its own procedures and demonstrated a failure to consider the relevant issues” – although the decision was still lawful.

Ms Williams said: “This case demonstrates the huge asymmetry and censorship that characterises public debate at the moment. Some people choose not to act on same-sex attraction. They should not be ostracised for doing so but helped, if that is what they choose. Mike Davidson and Core Issues Trust want to help those who experience same-sex attraction but would prefer to change that.”

The Court of Appeal is now expected to make a judgment on the case.