Teachers should ignore new rules on promoting British values, it was suggested today.

The regulations, introduced in the wake of the Trojan Horse scandal, are "totally out of proportion", according to Robin Bevan, head of Southend High School for Boys.

He said that no-one would argue against schools and colleges promoting personal morality and a sense of civic duty among pupils.

But the move to require schools to promote British values, such as democracy, tolerance and rule of law was ill-considered and an act of "political posturing".

Proposing a resolution on the issue at the Association of Teachers and Lecturers (ATL) annual conference in Liverpool, Mr Bevan also suggested that what constitutes a core British value can change over time, and raised concerns at how these ideas may be interpreted by a "future right-wing government, or a partner in that government".

Ministers announced last summer that all schools would be required to actively promote British values, a move that came following the alleged Trojan Horse plot by hardline Islamists to take over a number of schools in Birmingham. Ofsted checks that these are being promoted as part of regular inspections.

Mr Bevan told the conference: "There is no-one is this hall who would argue against the important role that schools and colleges play in promoting personal morality, in developing a sense of civic duty, in fostering engagement with our democratic structures or in embracing a wider global understanding."

Schools and colleges were already required to have a broad and balanced curriculum, and promote pupils' spiritual, moral, cultural and social development. These requirements have existed without controversy for some time and are effective, he said.

There had been a number of well-publicised instances where some staff in some schools had sought to promote a different agenda, Mr Bevan acknowledged.

But it is ill-considered to respond to these isolated incidents with a "headline-grabbing act of political posturing".

"Such has been the response, as schools are now obliged to promote fundamental British values," Mr Bevan said.

He added: "If these fundamental British values change with time, then they are hardly fundamental.

"And let's face it they have changed with time. We now allow women to vote. We no longer chemically castrate homosexuals.

"And if you think that's way in the past, it wasn't until the 1990s that marital rape was made a criminal offence.

"Fundamental values perhaps, but they are changing over time. We can hardly describe them as fundamental, we can hardly describe them as British.

"And it's not just a problem of definition, colleagues.

"Just take one moment to imagine how fundamental British values might be interpreted by a future right-wing government, or a partner in that government."

Mr Bevan later said: "Even more extraordinary is the notion that Ofsted will somehow be the agent of micro-fascism in assessing the extent to which schools actively promote these fundamental British values."

It is likely that Ofsted will only raise concerns about schools or colleges that have actually already breached existing requirements to offer a broad and balanced curriculum, the headteacher argued.

Calling on delegates to back a resolution asking ATL's executive to monitor how British values are being policed, Mr Bevan said: "There is the well-publicised issue of the radicalisation of a very small number of students. But the solution being proposed is totally out of proportion. It's the wrong approach, at the wrong scale, with the wrong model of learning and the wrong method of assessing its effectiveness.

"When it comes to the new requirement of promoting fundamental British values, including the role of law, here is one law that I would actively encourage you to disengage from."