“The problem was that the hall had become very institutionalised, so we had to restore it completely.

“We’ve also added Merseyside’s only five-star hotel rooms.”

Lord and Lady Derby (who was a former curator for the Queen’s Pictures collection) bought back furniture and objects sold off from the hall when its use changed.

But they were still dealing with a very old house, largely of the 1730s, yet with all the problems of organic expansion over many centuries.

Such a vast pile poses major problems of heat loss.

Not only is the Hall a listed building, but in its present role as a conference and events venue, its stately home look is essential.

Besides the restoration costs, there are the day-to-day running bills.

“This is a traditional, solidly-built property with thick walls and a big roof,” said Lord Derby.

“While it keeps some heat in, thermal imaging of the house showed the windows glowing bright red where all the heat was escaping from the radiators beneath them.

“We can’t get rid of the sash and casement windows, but we could put thermal shields behind the radiators to redirect the heat inwards.

“But the best heat saving measure is to close the original wooden shutters fitted to the windows.

“The roof space is in many parts, which makes it difficult to insulate properly.

“A house like this gobbles up heat and our old boiler house was some way from the house itself.

“At any one time, there was six tons of water flowing in pipes between the boiler house and the hall.

“Also, we’ve got a lot of Edwardian pipes beneath acres of floorboards that are amazingly difficult to lag

“Pipes are now pre-lagged and heat can be transported over several hundred metres without loss.

“Thankfully, there is an amazing efficiency difference between old and new boilers.

“It’s all about knowledge and having a coherent strategy.

“There’s no point in generating a load of heat unless you know why you’re doing it.”

Apart from routine practical matters of running a big property, there is a need to keep an eye on government energy policies.

“The big unknown from the government is feed-in tariffs,” said Lord Derby. “This is a sum of money for A bit of energy you produce, whether it’s for your own use or to sell.

“The Government won’t give you a grant to put in a boiler, but will give this feed-in money.

“If this goes ahead, it will be a significant change in economics for us.”

Other ideas under consideration are water source heat pumps and wood chip boilers.

“All these are feasible and the technology is getting better and better,” said Lord Derby.

“But all this equipment costs significantly more – about three or four times – than an ordinary gas boiler.

“Unfortunately, our Knowsley Park is too flat for hydro-generation.

“This is the most efficient green way to make electricity, as proved in Scotland and Wales.

“However, it might be feasible at our Crag Hall estate, in the Peak District.

“Probably the best idea at Knowsley would be the water source heat pump which extracts heat out of the water.

“We’re looking at the possibility of putting hundreds of metres of coiled hose pipe in one of the lakes so it can extract heat out of the water.

“It works like a sort of radiator in reverse and is successfully used in rivers.

“I think we’re merely at the beginning of understanding what we can do in these areas.

“The Mersey barrage debate has gone on for decades, as to whether this is good or bad ecologically.

“But there’s no doubt that the power of the sea is an enormous force which we should seriously consider harnessing.

“In just 10 years, all kinds of new technologies have emerged.

“It’s difficult to realise how new some of this stuff is.

“Even established green technology like wind turbines have moved on.

“The modern wind turbines are much quieter as they have less gears and create less friction.

“For example, vehicle technology which was once regarded as incredibly expensive developments for Formula One cars, like anti-lock brakes, cascades down to ordinary saloons. Or satellite navigation, which was James Bond stuff not that long ago, can now be bought at your local hardware shop for £50.

“All these ideas and projects interest me hugely and tick all my boxes.

“They appeal to my individual and corporate values about the responsibility we should have towards the wonderful planet on which we live. Done properly, it’s good for sustaining our business and the earth. It’s a win-win situation.”