Oxfordshire author Sheila Kitzinger says her daughter's High Court fight to have her gay marriage legally recognised in England is a question of justice.

University professors Celia Kitzinger, 49, from Oxfordshire, and her partner, Sue Wilkinson, got married in Vancouver, Canada where unions between same sex partners are lawful three years ago.

The couple, who live in North Yorkshire, want their marriage to be given full legal status in the UK and protest that it is "insulting and discriminatory" to be offered civil partnership instead.

They are now seeking a declaration under the Family Law Act that their marriage was valid at the High Court in London.

Ms Kitzinger's mother, the feminist pioneer and author, Sheila Kitzinger, 77, from Standlake, said: "At first I thought it all seemed a little trivial when so many terrible things are happening in the world, like the starving refugees in Africa and the carnage in Iraq, but I think it is extremely important because we need to look closely at the values we hold in our society and it is vital we have equality and don't treat anyone as 'separate but equal'."

She added: "I see the issue of marriage in a much wider context of justice, equality and race relations.

"I hadn't realised it until my husband told me, but his mother was an Arian who married a Jew, and Nazi Germany tried to anull her marriage because of this. My daughter's case strikes me as similar."

Mrs Kitzinger did not attend her daughter's marriage to Ms Wilkinso in Canada. But she said the women had sent wedding pictures and are regular visitors to the family home in Oxfordshire.

She added: "It seems very strange that Catholic countries like Belgium and Spain recognise their marriage, but England does not. My daughter is very upbeat and positive, and rings me regularly to give me updates on the case. She has also said that even if they are not successful, they would have at least raised awareness of the issue.

"But we are hopeful they will be successful, and when they are, we look forward to celebrating with them."

Celia Kitzinger and Sue Wilkinson's lawyers claim that failure to recognise a same sex marriage breaches the European Convention on Human Rights.

The Lord Chancellor, Lord Falconer, claims the wording of the Convention supports relationships between a man and a woman.

He argues that since the newly-introduced civil partnerships do the same, the women are not being discriminated against.

A civil partnership is formed only when the second of the two parties signs the partnership papers. This does not require a public ceremony or even have to happen at the same time as the first signature, whereas a marriage happens when the partners exchange spoken words and also sign the register.

Marriages can also be conducted by Church of England clergy, while civil partnerships are only conducted by registrars.