Who can tame this bewildering monster?

As the National Trust begins its search for a new leader, the time has come to take an imaginative leap

The head hunters are being found; the Rolodex of contacts is being consulted; the race to replace Dame Helen Ghosh as head of the National Trust has just begun. It’s a key job for an institution now routinely painted as in crisis. So who should get it?

Neither the answer, nor the job, is straightforward. National Trust members now number almost five million, making them a powerful force, if one with a host of different agendas. Then there’s the sensitivity of the position. The Trust has a unique role in defining our national identity – from fell walking via noble architecture and a lingering high mindedness to Victoria sponge. No other country possesses an institution that is remotely comparable in scale and scope. No other country would ever try to create one. Then there’s the undeniable fact that this venerable and precious institution is coming in for a great deal of stick. I even had a pop myself, a couple of years ago, about the lack of curatorial rigour in the country houses. Whether it’s bean bags at Ickworth House, a sensitive farm in the Lake District, the recent fuss over the requirement for volunteers to wear Gay Pride badges at Felbrigg, the stories add up – however unfairly – to give an impression of malaise.

Let’s begin with a job description. As soon as you start on one, you realise how impossible the task can be. The Trust is, as Henry James said of War

and Peace, a baggy monster, epic in scale and bewildering in variety. Open countryside, stately homes, opulent collections, writer’s retreats, Georgian mills, working class back-to-backs, holiday cottages, 618,000 acres of tenanted farmland, nearly 600 miles of coast – these are a vast inheritance, haphazardly acquired and requiring special knowledge, whether of watermeadows, tapestry conservation or (at Waddesdon) a musical automaton in the shape of an elephant.

And the responsibilities grow more numerous every year. Once the Trust was expected to do little more than care for its properties and open spaces. Now the park at Knole is a Site of Special Scientific Interest, home to a rare species of ant.

Not that the Trust’s director general needs to know every detail of the holdings: Dave Lewis, chief executive of Tesco, can’t know every jar of pickle in the store. But unlike Tesco, the Trust is not only answerable to its shareholders (ie members) but volunteers too. And you just can’t manage volunteers, it’s like herding cats – which is a problem because the Trust relies, wonderfully, on tens of thousands of them.

Next comes the key question. What’s it all for? Again, Tesco has a clear purpose – pile ’em high and sell ’em cheap, in the words of its founder. The Trust is riven by paradox and internal contradiction. The aesthetic camp is at perpetual loggerheads with the out-of-doors camp. Local distinctiveness is valued – but so are high standards of scholarship that can only be provided from the centre. Some visitors want a good day out, a place to let children off the leash or entertain the elderly; others expect a soul-refreshing experience of solitude in nature, or intellectual stimulation from historic displays.

Who is up to the task? With a salary of £185,000, we can eliminate chief executives of FTSE companies, who earn millions. The last two DGs, Dame Helen and Dame Fiona Reynolds, came from the civil service; they were used to running big departments but not, perhaps, giving inspiration. They both came with liberal agendas, and not much detailed knowledge of the properties. It’s time for a change.

To restore confidence in the Trust requires the leap of faith made by the trustees of the V&A when they appointed Tristram Hunt. Zac Goldsmith? What an opportunity for him to pursue his green agenda. A Tory wouldn’t harm. Simon Thurley, late of English Heritage, must be on the list; he’s an accomplished historian as well as TV performer – although English Heritage did undergo an amoeba-like division on his watch (Historic England now fulfils the planning function).

The front-runner for my money is the museum director Tim Knox; not only is he a famous connoisseur, but his partner, Todd Longstaffe-Gowan, is a landscape architect. This would be a loss for the Fitzwilliam Museum, Cambridge, where Knox has only recently become director. But the seemingly gentlemanly world of the Trust can also – witness the meanspirited savaging of Dame Helen – be ruthless.