I’m sure you will all be familiar with the sets of huge beacons that are outside and inside Portsmouth Harbour. You also probably know that these are to help the Navy’s new aircraft carriers HMS Queen Elizabeth and HMS Prince of Wales squeeze through the harbour entrance. However, have you wondered why in an age of technology that can pinpoint a letterbox from space you need visual leading marks? I have too, and you might find this video interesting. It is presented by David Goddard MBE FRIN (yes, the Goddard of the Goddard Beacons) and although it is rather slow and detailed, it does explain why they are needed and how they are used very well. Enjoy.