Classical Italian gardens must have excellent bones - like a beautiful woman, the cheekbones have to be right.
Sir George stuck to this principle, putting in long and perfectly trimmed yew hedges which separate the space into different rooms. Still and moving water is required - still to reflect sky and soften landscape, and moving for the sound of splashing spray; the large fountain that splashes into the bathing pool at the foot of the middle lawn, and the various marble candle fountains which enliven the side lawns manage this admirably.
Head Gardener David Kesteven came to Renishaw almost exactly 10 years ago, on November 1st 1997, when he was 30 years old. His first job then was to dig up the middle borders, and remove the bindweed that had taken them over.
Since then he and his small team of gardeners have maintained the gardens, keeping lawns and borders trimmed and weeded, planted and cared for.
But now, Lady Sitwell, who is often to be found in the garden with trowel and secateurs herself, and who involves herself with all its aspects, has decided that the time has come - as it does for even the most established of gardens - for a rethink.
Over the years - long before David Kesteven or Penelope Sitwell came to Renishaw - the gardens have been subject to lack of knowledge, lack of taste, lack of an overview and a consistent plan. Sir George's structure was good enough to hold fast, but the planting had become dull, with no variations of colour, definition or scale.
Enter Anthony Noel, author, lecturer and above all garden designer, whose aim is always to add a dash of seductive drama - a flash of high heels behind a curtain - a confident modernity that balances the original classical form.
He works on all scales - Renishaw Hall to Fulham courtyard - and his work is described by Tim Richardson in his major directory of the 500 greatest gardeners ever as combining "a penchant for theatricality and glamour with a sure handling of space . His original ideas have been copied many times over in recent years."
His own garden in London has captivated many.
". I would rate it as one of the most charming of small gardens anywhere" wrote Tony Venison in Country Life. Francesca Greenoak in The Times described it as "A garden with theatrical flair.a jewel-like garden.a masterpiece of exquisite artifice and perfectly trained plants.".
So when Penelope Sitwell met him, and talked of her aims for Renishaw, minds met. Including David's which says a great deal for everyone's love for Renishaw and their commitment to making a beautiful garden wonderful. David could easily have resented the newcomer and his involvement with the garden he has worked in wholeheartedly for the last 10 years. But no - he considers him his mentor, and is genuinely thrilled at the collaboration. Anthony is "fun, enthusiastic, humble and talks a lot of sense," says David, who has enthusiastically dug up the middle borders again, ready for redesign and replanting.
"Before Anthony arrived, I drew up planting diagrams of what there was in place, although these were soon discarded! Anthony really looks at what works , at the whole picture. We walked for two days, and he applied his good eye and his good taste to come up with a plan that is terrific." The evergreens are to be replaced, there is to be a grid of roses by the back door. Architectural features are to be echoed - the pyramids on the corner of the hall are mirrored by box pyramids in the garden below, for example, 15 altogether, between the windows.
David bubbles with enthusiasm:
"The planting is going to be bold, with architectural full stops. Blue and yellow and white in big blocks, using stipa gigantean to create bays, in which will be planted tradescantia, achillea and ajuga. Variations on a theme, like looking into a paintbox. The foliage has already started, and is showing potential. By June, July and August it will be there. We have got the plants already you see - excellent stock, and we can use big specimens in big bold swathes.
"Anthony keeps saying 'simplify' and 'what's that doing there?' He makes me think, and makes us both ruthless. 'Think of the foliage' is another one, and above all, 'plant like you mean it.'" Anthony Noel relishes his commission. He is not frightened of the scale of the project, and has thrown himself into it with delight.
"There is lots to do," he says. "It needs drama, and to develop and look beautifully trained. The planting has been sorted out, and theatricality restored, with a modern twist. It's much more structured than it has been, much more like Sir George's original. It is bolder too; it lost its confidence over the decades, and simply needs taking in hand - rather like a naughty, talented child."
The candle fountains are being restored, the lines of the dark green hedges are being crisped up. Lady Sitwell is keen on flowers, so flowers there shall be, although Anthony believes that the original design is so strong that flowers are almost superfluous."
The gardens open at the start of the season, on March. It will take a little time for the full power of the renaissance to show, but there will be something to see all over the summer.
Above all, here is a rare opportunity to observe how the skill of a gardener and the taste and flair of a designer blend with the vision of an owner with taste to restore one of the most original and visually harmonious gardens in the country, and allow it to have the impact it deserves.
SH