In 2006, Andy and I took our mountain-bikes up to Inverness and spent a week riding an off-road route to Fort William, which we had put together from detailed Ordinance Survey maps.

Mongolia is a far more accessible place for a mountain-biking expedition than I’d imagined. Navigation has been a mixture of old techniques and new technology.

Her familiar, tearful, smiling face was framed by the tinted window, then a silhouette, receding; finally she joined the flecked shapes swaying within the departing bus as it began its 24-hour journey to Tehran.