Denver Sluice, south-west Norfolk.

Denver Sluice is in fact a complex of three sluice gates which control the flow of water between a series of large drainage canals dug between the 1630s and the 1960s to drain water from the Fenlands to the River Great Ouse, to reduce the flood-risk to the region and to prevent further ingress of tidal waters from the Wash. The most recently dug drainage canal post-1953 also canalised the lower River Wissey, a tributary of the R. Great Ouse which drained the ‘outlier’ fenlands of Methwold Hythe and Southery and Hilgay Fens. In walking from one side of the complex to the other it is hard to unravel which channel is which but there are information boards erected by the Environment Agency and a copy of the relevant OS map helps.

Although each channel is very wide they are no longer arteries of trade although pleasure craft can pass through the incorporated locks.

These drainage channels have led to the transformation of the Fenlands from natural wetland to a huge tract of fertile arable land. A rare thing – a landscape that is actually ‘flat’.

Number three, see above.