The Cromwell Weir tragedy happened on September 28, 1975, when a Royal Engineers assault boat on a night-time exercise went over Cromwell Weir on the River Trent, killing all but one of those on board. Cromwell Lock and Weir is a huge concrete engineered construction marking the tidal point of the River Trent. A memorial service to mark the 50th anniversary of the tragedy will take place at the lock, near Newark, today (Sunday). “We went out of the lock and turned a hard right, into the thunderous roar and spray below the weir. The four tray mortuary at the old Newark Hospital was overwhelmed, as was the retired GP who carried out routine post-mortems.