English Heritage (BBC2, 9pm)

TWO muscular young men wearing loincloths are being raised in the air by a forklift truck in a warehouse.

They stand on a column, holding a very large ball on their shoulders. Onlookers take pictures and discuss the merits of them holding a large bowl rather than a ball.

They are modelling for experts, of both an artistic and structural nature, from English Heritage.

This is all in the cause of art – they want to see what the marble fountain at the centre of a proposed Elizabethan garden at Kenilworth Castle, in Warwickshire, will look like.

English Heritage is spending £3.5m on the project and, before you start complaining that’s a very expensive fountain, I should explain that the water feature is only part of the plan to recreate the garden built in 1575 by Robert Dudley, Earl of Leicester.

He wanted to impress Queen Elizabeth I when she came to stay. The monarch and the Earl were more than good friends.

He was her favourite courtier and her lover. Instead of giving her flowers, he gave her a garden during a planned 19- day visit to Kenilworth.

Alas, the date went badly. No sooner did she arrive than she humiliated him by slapping him in full public view. This was understandable as she discovered he’d married in secret two weeks previously.

I’m surprised she didn’t cut off his royal privileges, or Bobbit him, as it’s known in the trade.

These days there’s not much to see there, just a few castle ruins. Recreating the garden will help boost visitors or “revolutionise what people get from Kenilworth Castle”, as English Heritage chief executive Simon Thurley puts it.

English Heritage is the official guardian of more than 400 historic sites and Thurley is “shaking them up with a more active approach to history”. If modern regulations permit. Even on a visit, he’s required to take a 20-minute health and safety induction course before setting foot on the construction site.

As well as a fountain, the Elizabethan gardens feature an aviary, obelisks, arbors and huge terraces. Not that anyone is too sure what the original looked like.

All they have to go on, apart from a few bits of physical evidence, is a letter written by a witness called Langham.

The garden being recreated, says properties presentation director Dr Anna Keay, is a “reasonable, justifiable and arguable interpretation” of what was there.

Who’s going to argue? “We’re not going to discover a photograph of the garden,” she points out.

It emerges that lots of people will argue on any number of matters, from whether the “boll” in the letter means bowl or ball, to who’ll pay for the steel to reinforce the wooden structure.

Despite two years of research, the project is still dogged by indecision. And the building contractor goes bust two weeks before work is to begin.

Contracts manager Vernon Clews- Jones, from the company that takes over the job, remains cheerful, despite getting behind schedule and the budget rising.

When experts decide a stone wall looks too modern, he gets a mason to chip bits off to give a weathered appearance.

Modifications are forced because of safety issues, something that Dudley didn’t have to worry about for what was intended as a temporary decoration.

More alarming is the revelation that Langham’s letter could be inaccurate and he might have been “not entirely sober” when he wrote it.

He and the other Kenilworth guests certainly didn’t see the road and cars from the terrace as today’s visitors do.

Thurley finds the view “distressing”, although having to do that health and safety course irks him even more.

It all culminates in war over who’ll pay for the extra structural work. Whether the end result is worth it will be up to visitors to the garden. But this fascinating behind-the-scenes documentary does ask an important question: is it possible to recreate the past while living in the present?

Answers on a postcard, please.