Lord Young of Acton, the founder of the Free Speech Union, has tabled a number of amendments that would stop pub and university bosses having to ensure their staff were not subject to harassment by overhearing opinions they did not agree with.

The Times revealed in January how pubs could ban customers from speaking about contentious beliefs such as religious views or transgender rights over fears of falling foul of Angela Rayner’s workers’ rights reforms.

Ministers have proposed that employers must protect workers from being harassed at work by “third parties” such as customers or clients. If they fail to do so they could be sued.

Young is hoping to tweak the laws so that opinions on political, moral, religious or social matters are exempt from the law as long as that opinion is not “indecent or grossly offensive”.

The Conservative peer said the way the law was drafted would mean an employee could take offence on behalf of another employee even if he or she did not hear the comments made.

For example, if a male bartender overheard a conversation between customers that was potentially considered as harassment towards women, the business owner would be expected to take action.

Young said the issues could even extend to sports venues. For example he said shouts of “are you blind?” were often levelled at referees.

He told the Times: “It’s not clear exactly what reasonable steps publicans and public business owners will be expected to take.”

The Times previously revealed how the Government was warned by the equalities watchdog that rules could “disproportionately curtail” freedom of expression and be applied to “overheard conversations”.

Ministers admitted in a human rights assessment that there may be issues around freedom of expression “particularly in areas of legitimate debate which are carried out in a contentious manner”.

But the Government said: “The Employment Rights Bill will not affect anyone’s right to lawful free speech, which this Government stands firmly behind. Upsetting remarks do not fall within the definition of harassment. We are strengthening workplace protections to tackle harassment and protect employees from intimidating and hostile abuse as well as sexual harassment.”

Luke Johnson, the hospitality entrepreneur behind the success of Pizza Express and The Ivy who is now executive chairman of Revolution Bars, told the Times he feared that would not play out in reality.

He said: “The unintended consequences of ill-thought through legislation like this could be very damaging, not just to the pub trade who will have to restrict speech and police it and all the rest of it, but to our very way of life.”

He added: “For hundreds of years people have been able to meet in the pub and have a good old ding dong about whatever it is. Anything from animal rights to the latest tyrant who’s in power in Westminster. I cannot believe this is the purpose of it. But knowing how litigious employment law is these days, I’m afraid litigation and then restrictions feel almost inevitable.”