Ouse Washes, Cambridgeshire.
An area of water meadow used for grazing in summer and water overflow and storage in winter. It is about 20 miles long and contains the Old Bedford River within its north bank and the New Bedford River within its south bank. It branches away from the Great Ouse at Earith and runs north-east past Mepal and Manea to rejoin the Great Ouse near Downham Market.

Engine Bank is the part of the north bank of the Old Bedford River for a few miles north of the A142 road bridge at Mepal.
Access is by public footpath from unofficial parking space just north east of the bridge.

The north bank passes through an RSPB reserve on either side of Welches Dam where there is a car park. Access is from Manea.

Wall Butterflies have been seen on Engine Bank and near Welches Dam.

Personal sightings:

31 July 2011. Engine Bank, Mepal. Late morning to mid day. Bright intervals, fairly windy. 4 Small Coppers, 2 Common Blues, 1 Wall (female), several Gatekeepers, few Meadow Browns.

2 Aug 2011. RSPB Area, Welches Dam. Mid to late afternoon. Bright intervals, hot, humid, no wind. Frequent Common Blues, Red Admirals and Peacocks, 1 Wall (male by the pumping station), few Meadow Browns, frequent Gatekeepers.

2 Aug 2012. Engine Bank, Mepal. TL4381 and TL4481. Mid day. Bright intervals, fairly windy. 1 Small Tortoiseshell, 2 Peacocks, 1 Wall (TL440818.), 3 Gatekeepers, 2 Meadow Browns.