Unable to answer "What’s the topic of this information board?" – Clifton Ings Flood Alleviation Scheme (Information Board) – https://osm.org/node/11148469417 via StreetComplete 57.2:

See photo. Clifton Ings Flood Alleviation Scheme. There is also a cycle path finger post next to it.

Attached photo(s):
https://westnordost.de/p/208644.jpg