I’m told Susan Bennett and Earl Hyde have a Gothic compost heap in their garden in Muswell Hill in North London, and I have to go and see it. Well, wouldn’t you? At 11am I ring the door bell and before you know it Hyde is sitting me down to a couple of superb lemon pancakes – my breakfast as it happens. He and Bennett are potters: they work from home and lead a very civilised life at their own pace.

We talk Gothic heaps. The stained-glass arch came from a chapel being demolished down the street, and Hyde salvaged it for a rainy day. He is a great skip man and all the plywood for his shed came from skips. Tatty? Never did you see a garden shed like it: it has a high mansard roof somewhere between Second Empire and the Psycho house. Where cast-iron finials run round the roofs of the Palace of Westminster, Hyde has a little plastic fence from the Pound Shop that’s supposed to stop border plants flopping forward on to lawns. It does the trick perfectly. The nearby Baroque temple, with lapis marbled pillars made from drainpipes, is fit for a pope.

Now, a shed like that can’t sit next to a compost heap, a wheelbarrow and piles of pots. The heap needed to have a similar and appropriate dignity. Then Hyde thought of the stained glass. Why not a Romantic compost heap, a Gothic ruin? And so the glass was patched up and Hyde set to work making a ceramic moulding to surround it. You would swear it is stone, but Hyde’s speciality is “architectural” pottery and his 2ft lustre-glazed Wurlitzer has to be seen to be believed. The detail is tremendous.

“Where’s the ash glaze, Susan?” asked Hyde, ready to fire his “stonework”. “Over there,” said Bennett, busy with something else. It was the wrong ash and the stonework turned out lilac; not what you want in a picturesque ruin. So Hyde had another go and this time it was just the right stone colour. Build a low stone wall, erect the glass and ceramic mouldings, and there you are: a ruin, and no compost heap in sight.

But it would have hurt Hyde deeply to have put something so interesting as a mauve window into a skip. So he worked on the colour, toned it down, and erected it in the bushes 10ft above the first window, filling its opening with mirror instead of stained glass. When we stand close beneath it, gazing down the imaginary nave, all I can see are reflected trees and the sky above, as if there were no mirror there at all. Eat your heart out, Ruskin.

Atop the window’s side pillars are little stone corbels where, in a cathedral, there might be gargoyles. In this case there are the heads of two of their beloved Weimaraner dogs. Hyde suggests two Karl Marxes could have been fun. I suggest two busts of Prince Charles with only the outside ear on each one, like wings.

Outdoor mirrors are a big thing for Hyde and Bennett and I have never seen them better used. The garden ends in a Chinese wall capped with green glazed tiles, where mirrored, red-lacquer doors wrapped in foliage seem to make the garden go on for ever. “That’s the Forbidden City,” says Hyde. “I built it to hide Susan’s potting-up area.” Some hope: boxes of plants spill out everywhere, because they open for the National Gardens Scheme and are keen to generate funds for it.

My visit has overrun, chatting away, and Hyde rustles up crab soup and a salad as if it were nothing, followed by a slab of his famous NGS fruit cake. “When we open,” says Bennett, “the teas are supposed to start about 4pm, but they’re always there queuing up at 2.30, desperate to get started.”

So what drives them to open? Hyde hesitates for a second. “Part of me would like complete privacy,” he says, “but part of the attraction of NGS opening is that there’s no political angle, no church angle, it’s just for charities. But we do open for a refugee organisation that we feel strongly about, too.” Mostly, they just enjoy a busy day and seeing other people enjoying their garden.

Bennett is actually an official organiser for the NGS. It is part of her job to find new gardens for the scheme. A challenge, then? “Yes, it is. I was scared it would be impossible, but word of mouth puts you on to new people, and only one person I asked has said no.”

Returning to the subject of Compost Abbey, I suggest putting a light behind the stained glass, “For when you’re eating out late in the garden. The glow of nature triumphant! Noble rot!” And realising just what delight their garden provides, I say to them, “Would you mind if I wrote a piece about the compost heap?” “Thank you but no,” says Bennett, suddenly serious. “We don’t want to talk shit.” Well, at least I tried, I offered. It’s a shame. Then the smile breaks… “Of course you can.” Dammit, they got me there.

Open for the NGS (go to www.ngs.org.ukor call 01483 211535 for details) on July 27, 2pm-7pm, and by appointment

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