Later this month, in line with ancient law, a bundle of straw will hang from the top of the huge Barking Creek flood barrier. The Barking Creek barrier in east London is a huge concrete structure built in the early 1980s with a large barrier gate that can be lowered to protect Barking from flooding coming up the Thames.

But it still needs a bundle of straw to be hung from it later this month, because ancient laws say so.

This ancient law applies as the barrier part of the Port of London Authority (PLA), and if the headroom above the river is ever restricted for short term works while the river is also kept open, then a warning has to be added to the bridge or barrier to warn ships that may pass under it.

And thanks to ancient laws, that warning to mariners takes the form of a bundle of straw.

This will be needed, as on or about 27th March 2023, contractors working on behalf of Team 2100 will be erecting scaffolding across the top of the Barking Barrier.

According to the PLA, there will be scaffolding on both towers which will be erected predominately on the land until it reaches 37.3m above Chart Datum, thereafter it will move into and over the span on each site reducing the available air draft by 3.1m.

The barrier is a very tall structure, and it would be a very odd boat that is both shallow enough to sail up the shallow Barking creek, and yet also tall enough to bang its head on the top of the Barking Barrier. But laws are laws, and when the height is reduced, a warning is needed.

And hence, in accordance with Thames Byelaw 36 (pdf), a bundle of straw and a fixed white light will be suspended from the scaffolded areas to indicate a reduced height.

If you ever needed a reason to visit the Barking Creek barrier, early April would be a good time to do so.