ON THE face it, you might not think a play written amid the rigid social conventions of the Edwardian era would have many parallels with our hectic modern age.

Yet Tessa Peake-Jones believes not only that the play is universally relevant, but that it strikes a chord with the internet data harvesting scandal that has stunned the nation in recent weeks.

The Cambridge Analytica furore has raised questions about the security and motives of the institutions we had put our trust in. In this sense, says Tessa, The Winslow Boy tells a cautionary tale.

“People come out of the play and say, ‘nothing has changed, we still need to fight those battles’”, says the actress, famed for her role as Raquel in Only Fools And Horses. “He [Rattigan] is having a go at big institutions and saying there is a morality in fighting for justice.”

The Winslow Boy revolves around a young boy who is expelled from the Royal Navy College for supposedly stealing a five-shilling postal order, leading his father (played by Aden Gillet) on a brave quest to clear his son’s name.

Much of the action takes place in a courtroom as Arthur Winslow, supported by his wife Grace (Tessa’s character), rails against the authorities who have incorrectly persecuted the boy.

“Audiences say to us, ‘it’s the same as today,’ but now the powers are Google, or Facebook,” says Tessa. “There are always people willing to speak out against such institutions.”

Which leads us back to Cambridge Analytica, and the whistleblowers that have gone to the press with their inside knowledge of the mass data breach.

“That’s certainly something I’ve been thinking of,” says Tessa. “I was reading more and more about it in the news when it broke. It’s a different age to Rattigan’s, but the fact our information can be used and abused is alarming.

“Speaking as somebody who remembers a time before the internet and even mobile phones, we always knew that technology was a double-edged sword.”

Tessa remembers dinner parties with friends decades ago where the recurrent topic of conversation was the web, and how, if it all, it would be policed.

“I don’t know the answer to that – I don’t know how you can control it. It seems almost impossible to protect the information we have online.”

Tessa talks of trying to teach her now grown-up children to use the internet in a careful way. The actress has a natural advantage in playing Grace Winslow as she has successfully navigated the business of being a mum. In Rattigan’s script, Grace is a “gentle, softer” counterpart to her fiercely tenacious husband.

“She empathises not just with her son but is able to see the cost that the whole thing is having on the family and the health of her husband,” says Tessa.

“She wonders whether letting this battle go would actually be better for the family. If this had happened to my kids, you’d wonder which course of action would be best for them.”

It seems obvious that fans of Only Fools And Horses would turn out in force to see Tessa perform, although she points out that it is hard to identify these people.

“It’s a very difficult question to answer – you’d like to think that some come for that reason and others because of the enormous pull Rattigan has.”

With David Jason, Tessa formed one of the most affecting screen relationships in UK television history on Only Fools And Horses. She is gratified that the show keeps reaching new generations.

“What’s extraordinary about John Sullivan’s creation is we all get letters from people each year from young people saying they love it,” she says.

“If John could see that he would be absolutely thrilled. In any walk of life, how often does somebody come up and thank you for what you’ve done?”

Sue Holderness, who played Marlene in Only Fools, is starring in Quartet at the Theatre Royal this week and Tessa jokes that the two woman are inadvertently “following each other around” on the touring circuit.

While Tessa will always be best known as Raquel, her role in the enduringly relevant Winslow Boy proves she – along with Rattigan’s play – is more than capable of moving with the times.

The Winslow Boy
Theatre Royal Brighton,
April 23 to 28, atgtickets.com