BACK in March, David Roberts, head gardener at Knebworth House, said a blistering summer was on the horizon. But when late frosts, monsoon bursts of rain, Arctic temperatures and the coldest winter for a decade still refused to allow spring to emerge, his

BACK in March, David Roberts, head gardener at Knebworth House, said a blistering summer was on the horizon.

But when late frosts, monsoon bursts of rain, Arctic temperatures and the coldest winter for a decade still refused to allow spring to emerge, his words fell on deaf ears.

That was until the thermometer hit almost 100F and endless weeks of cloudless skies and heat baked our land dry, turning lawns into straw and the landscape into a dustbowl.

Mr Roberts' exact words in The Comet, having studied the trees in Knebworth's garden were: "The yew indicates our summer could be a scorcher."

This week he made a forecast that should send a chill down all our spines when he looked at the holly laden with berries in the wilderness garden and said: "I have never seen so many berries on the holly which signifies a very bad winter."

Mr Roberts, married with a teenage son, has been head gardener at Knebworth for the past nine years and, with his staff of four, keeps the 28 acres of garden with its history going back to the mid 1600s immaculate.

The task is not easy when you consider 90,000 people a year tramp through the garden at the rear of the stately home during the summer season, many leaving their mark in ways that often make him angry.

"Some people just like taking a souvenir," said Mr Roberts, 51, who was bitten by the gardening bug as a boy when his father was a vicar in Chesterfield.

"I suppose they go home with their plant and immediately know where each plant has come from when they look at their garden."

When he left school he pursued a career as an optician, even though he had enjoyed gardening as a hobby. That ambition quickly dimmed and he returned to the great outdoors, becoming a zoo keeper and forester.

Gardening as a profession soon surfaced in Kent where he stayed until setting roots at Knebworth.

"The design for the old gardens was laid in 1650 and expanded during the grand gardening era of Victorian times and progressed further in the early 1900s," he said.

"It has its challenges keeping it nice and tidy and trying to keep the rabbits out. But it is a job I love.

"My normal working hours are 8am until 4pm but sometimes during the summer I can start as early as 5am and can even be watering late at night.

"No two areas of the garden are the same. There is so much variety I never tire of the job. Some evenings I walk up from my cottage on the estate and walk around the garden alone. It is a wonderful end to any day."

The long hot summer has brought many changes in the garden and could be responsible for the future plants that will be seen at Knebworth where the hosepipe ban has been observed and water is carried around in large containers by tractor.

"I felt we had a moral obligation regarding not using hosepipes when local people can't use theirs but we have coped. We are still desperate for water even now and I believe we always will be," said Mr Roberts.

"We could have a major problem next year if we have low rainfall over the winter months. You can walk around parts of the garden now and it is bone dry, especially under the big trees.

"We are virtually in a drought situation and it is not good for plants. The normal English garden will have to change like the climate. Roses hate the heat so in 10 years time we may not see them in gardens.

"We will grow more plants that are drought resistant. More exotic Mediterranean plants will be seen. We have grown beautiful banana plants here this year and they have been wonderful."

The Indian summer that lasted until the end of October has already initiated strange events among the garden's plants.

The giant 100ft redwood, which is over a century old, has for the first time begun to flower in autumn when it should be showing signs of bloom in March. And in the walled garden, revived as a labour of love by Mr Roberts in 2000, the plants show no signs of winter approaching.

New shoots sprout from herbs and the strawberry beds still show clusters of heavy red fruits as though it is late summer.

In the large greenhouse the vines, some a century old, are still heavy with clusters of grapes now being feasted on by wasps enjoying the last of the summer Knebworth wine.

"You only have to look around to see the changes the hot weather has made and how the plants have reacted to the late warm weather, the plants are confused. Aren't we all?" said David adjusting his sunglasses against the brilliant sunshine.

"We could still pick strawberries in November which is fantastic."

But the sight of the holly with its scarlet berries and Mr Roberts' warning of what nature is telling us could mean a long cold winter is just around the corner.