Codename ‘Hillside’ - and the inspiration behind The Map Maker’s Promise

Tucked away in a Chilterns valley in Buckinghamshire, Hughenden Manor is a classic National Trust property. Once the country retreat of Benjamin Disraeli, its gothic interiors are infused with the enigmatic Victorian statesman’s personality. The Manor witnessed 18th-century political drama and visits from Queen Victoria – and, later, became the HQ for map-making in World War Two.

But the Manor kept this a secret for more than half a century.

When the Air Ministry requisitioned Hughenden in 1941, the war was not going well for Britain. We stood alone with our Commonwealth allies and Bomber Command was losing 44% of its crews – all volunteers with an average age of 22. Much of the bombing did not hit the intended German infrastructure and we needed a strategic way to shorten the war. We needed accurate target maps.

The Air Ministry recruited artists, cartoonists, commercial map makers, architects, graphic designers and printers who, along with RAF men and women – 100 staff in total – reported to Hughenden, the top-secret location codenamed Hillside. Aerial photographs were examined, targets identified, and checked at Hillside against
existing maps – a job I allocated to my character Clare in The Map Maker’s Promise.

In drawing offices, set up in Disraeli’s old Music and Dining Rooms, and even his wife Mary Anne’s Boudoir, draughtsmen and women each produced two maps a week. The target – be it factory, dockyard, railway or the Sorpe and Mohne dams (of the Dambuster raids) – was set in middle of the map and painted in magenta. Roads were black, water white, woods grey, so that the navigator and pilot could see them in the dim cockpit light to increase the accuracy of their missions, albeit with a sobering postscript. As Kathlyn Williams, who worked at Hillside, said: ‘With our paintbrushes we had helped to kill people we did not know.’

When the Air Ministry cleared out of Hughenden in 1946, they left behind some photographs of people working at drawing boards. The National Trust found these puzzling pictures when it took over in 1947, but it wasn’t until 2004 that the unravelling of the war secrets of Disraeli’s former home began. A room steward happened to overhear a visitor, Victor Gregory, telling his grandson about what he had done there during the war. Eventually, the Ministry of Defence agreed to release those who’d worked at Hughenden from the Official Secrets Act. Only then were they able to talk about their time there.

I visited in November 2022 to discover for myself the secrets of Hughenden, so that I could weave them into The Map Maker’s Promise. I absorbed the atmosphere of this fascinating place, to create the story I wanted to tell and convey what it might have been like to carry out this highly sensitive work at such a crucial time in our country’s history.