The London Borough of Islington has decided it will appeal against an employment tribunal ruling involving civil partnerships.

“The decision was taken after careful consideration of the legal ruling made by the London Central Employment Tribunal,” Islington said in a statement.

Lillian Ladele, a marriage registrar, claimed that she was discriminated against because of her religion when she refused to conduct civil partnership ceremonies while employed by Islington council.

An employment tribunal agreed. Her victory could set a precedent that will allow people with strong religious convictions to opt out of the provision of services to gays, lesbians and bisexuals.

Ms Ledele, who had worked for the council for more than 16 years, initially swapped with colleagues to avoid performing gay and lesbian ceremonies after civil partnerships became legal in 2005.

After formal complaints were made against her, an internal disciplinary investigation began.

She was shunned by colleagues, branded homophobic and threatened with the sack.

Councillor John Gilbert said: “We believe an important question is at stake and the law must be clarified.

“Islington Council, like all councils and employers, needs to know whether we can expect employees to provide services to all sections of the community, regardless of who they are.”

Gay equality organisation Stonewall said it will “seek to intervene formally in any appeal process if the opportunity arises.”

London MEP Baroness Sarah Ludford, the Liberal Democrat European Justice & Human Rights spokeswoman and former Islington councillor, welcomed the council’s decision to appeal.

“The case raises important issues about how second-class treatment of gay people as customers can be avoided if a services employee invokes a religious reason for displaying prejudice,” she said.

“If the staff ‘conscience clause’ endorsed by this tribunal ruling stands, a coach and horses will be driven through the existing UK and planned EU bans on discrimination.”

The decisions of the employment appeal tribunal set precedents and may be used in support of future employment tribunal claims.