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
Kids Company founder Camila Batmanghelidjh has responded to allegations of child abuse and sexual offences against the charity.
A thousand Italian musicians performed Learn To Fly in a bid to bring the Foo Fighters to their city and appear to have won over Dave Grohl.
A cat owner has spoken of his joy at being reunited with his beloved moggy - whose unique cross-eyed condition means he often gets lost.