Once upon a time, I worked at a theatre.
One of the most troubled parts of the whole building was once, in the nineteenth century, a nursery where there had been a fire. The consequences were unbearable; loss of young life and a trail of guilt and self reproach.
It was a studio theatre now, painted matt black from top to toe, and there were times when it sat fallow between productions.
It was at one of these times that I was visiting technicians there; and they showed me that this room was not just a great black box, but that it had towering floor to ceiling black shutters. If you undid them they revealed glorious windows. Light would flood into the space.
Three sets of shutters, there were: I opened one, and two, and gazed out upon the intricate knot garden below, watching toddlers career round the hedges in happy crazed delight. It was normal: a million miles away from the strange stilted atmosphere of this upper room with its unhappy history.
What a huge relief to see daylight and life! I had underestimated the oppression of the darkest chamber in the mansion.
And then I came to the third great window and my elation froze. For the strangest thing: there was very little glass in it.
Instead, ivy had grown up into the space and destroyed the man-made transparent barrier utterly. It had raged through the space, creating a dense matted veil within the frame. Somehow, the window – blinded by ivy – seemed rude: obscene.
A veil of leaves.
It was Thomas Gray, the eighteenth century poet, who wrote so beautifully of a country churchyard and its tranquil silence as the day ends:
“…All the air a solemn stillness holds,
Save where the beetle weaves his droning flight,
And drowsy tinklings lull the distant folds;
Save that from yonder ivy-mantled tower
The moping owl does to the moon complain….”
There it is: the reference to ivy as a mantle: a cloak; a covering. Ivy, if it is left to its own devices, can envelop a building entirely. It can flourish at heights of up to 30ft above the ground; its small suckers can cling tenaciously to walls old and new. For millennia it has been mantling our architecture.
It seems to utterly overwhelm man’s attempts at ordering his environment.
While folklore has looked upon ivy kindly – it was a sign of fidelity from the times of Ancient Greece onwards, and seen as an antidote to intoxication – it has been demonised in the culture I inhabit.
It is poisonous, they say: it is invasive. Its little tendrils can work their way into walls and pointing, and destroy structure; the rootlets leave markings on the stone. It can lift slates and invade neighbouring properties.
Sir Lionel Earle, Secretary of the Office of Works in 1923, said while working on a Windsor Castle project: “I also think that all the ivy on the walls should be cut. I believe the Queen favours such a policy. Ivy is a rank and odious plant”
And yet, our custodian of listed buildings, English Heritage, has just performed an extraordinary about-turn on the subject of this swarthy creeper.
EH commissioned researchers at Oxford University to study the effects of ivy on walls at five of their sites. They used complex monitoring equipment to measure temperature and humidity in the microclimate created by the dense mantle of ivy.
The researchers found that the ivy actually protects walls like a thermal blanket, warming them by up to 15 per cent in cold weather, and cooling in hot weather by 36 per cent. Ivy covered walls were less prone to the damaging effects of freezing temperatures, temperature fluctuations, pollution and salts than exposed walls without ivy.
Now they’ve built a wall specifically for research at Wytham Woods in Oxfordshire. It has different flaws built in so they can monitor the effects on a wall with, and without ivy.
But the mantles can envelop something entirely: this report of an English Heritage Seminar held in 2010 shows how the special features of a building can be swamped by such a blanket.
Rochester Castle is a case in point: at the end of the nineteenth century it resembled a green hulk, looming over the town of Rochester.
These days the stunning detail of forgotten windows, graceful wall arches and the holes which would once have held joists secure are there for everyone to see: for conservationists hold dear the quality of intelligibility: can visitors, however humble, see and understand something of the past from a building?
And so some buildings may remain mantled in ivy like treasured artefacts covered in sheets in some great mansion.
But wherever we see it, we will know: it’s there for a reason.