The staff at Hook Lighthouse — the world’s oldest intact and operational lighthouse — were surprised on Wednesday when they received a letter inside an A4 envelope with no written address on it.

The only instruction left by the sender was a hand-drawn map of the area with “Here please” written on an arrow pointing to an illustration of the lighthouse on the map.

It transpired that the letter had been posted by Dubliner David Curran, who documents on his blog, Me Versus An Post (meversusanpost. tumblr.com), how An Post fares with the various challenges he poses.

Ann Waters, manager at Hook Lighthouse, said the post was delivered just one day after Curran had posted it.

“We were very amused at the letter delivery and totally intrigued about the story behind it,” said Waters.

“We were very impressed with our postman’s map-reading skills. The letter told us that David loved Hook Lighthouse and that he had recently visited us; it also asked us to let the sender know if it had arrived and it was signed by David and also included David’s Twitter handle, @iamreddave, so we tweeted him about its arrival,” she said.

A postman of 20 years, John Whelan, said it was a unique challenge.

“I have never delivered a map-addressed envelope before. We often get letters with very vague addresses but this isn’t something you see too often, it wasn’t too difficult to work out where to deliver it to; there aren’t too many lighthouses like the Hook,” said Whelan.

“We always try our very best to deliver all post and if we can’t deliver something, a sticker goes on the package to say ‘no such address’. However that would really be the last straw.”

Other challenges Curran has set delivery services include a letter posted within a picture frame; a correspondence sent to the ringmaster of a circus using the address of the car park hosting the event at the time; and a letter where the numbers were omitted from the address. This required the postal worker to solve a sudoku puzzle to complete the address.

All three were delivered.

Hook Lighthouse has been operational for over 800 years. The first beacon on the site was lit by a 5th century Welsh monk, Dubhan, who established a monastery nearby.