The Duchess of Cambridge was sent signals similar to those sent out by the enemy and interpreted at 'spy school' Bletchley Park during the Second World War.
Her grandmother Valerie Glassborow worked at the famous site as a civilian member of staff, probably a duty officer, with her twin sister Mary.
Kate's visit marked a year-long restoration project at the Buckinghamshire site.
More top news
Spain and Portugal have seen an increase in bookings from British holidaymakers amid fears of terror attacks at other locations.
French labour strikes are threatening to bring the country to a standstill by blockading fuel supplies.
David Cameron has described the Institute of Fiscal Studies as a 'gold standard' group of experts, as it warned of 'Brexit' dangers.