The dome is Castle Howard’s defining architectural element. The enormous lead-lined cupola rises up from the stone lantern which is surrounded by a ring of gigantic busts. But the apex to the building is the small wooden lantern above the cupola, which in turn has its own little cap topped by a large carved finial. The last time the dome was covered in gold leaf was in 1997, and before that in 1961 when the dome has been rebuilt after the fire of 1940. Gold is sufficiently resilient that a covering can last several decades, but it is now time to revive the glittering summit of the house with a new application.

The lantern with its eight windows, and the finial above, are currently swathed in scaffolding and sheeting as work begins. The surfaces have to be rubbed down and painted, before a size is applied. Once this has dried the gilding process can begin. The area, measuring 32 square metres, will be covered in 23.5 carat gold leaf, which comes in the form of small booklets, measuring roughly 9 square centremetres, each containing 25 sheets of gold leaf on a backing paper.

The techniques for applying the wafer-thin gold can vary: in 1997 tiny square sheets of gold leaf were brushed onto the surface, this time a transfer method will be used. Each sheet will be pressed to the surface and rubbed to remove the backing paper, and the gold then given a smooth finish with a very fine brush. This process is painstakingly repeated, applying squares of gold-leaf, one-at-a-time, until the entire surface has been covered. The dome will require nearly 40 booklets of gold leaf, but the 23.5 carat gold is of such a quality that it does not have to be sealed against tarnishing, and is sufficiently robust to be able to withstand weather and pollution for the next several decades. Approximately 1,000 sheets will be used, but the gold leaf is so thin that the entire weight of the gold used comes to a mere 16gms. This would be roughly the equivalent to the weight of a medium-sized bracelet; or if it was rolled into a ball it would be a similar size to a marble.

When finished the lantern will light up in sunlight like an enormous golden beacon, visible for miles around, and act as a truly fitting pinnacle to this most splendid of buildings.