Unfortunately the information about there being no byelaws may be incorrect. Although Drone Scene shows Elvaston as being the in the South Derbyshire District Council area, the property itself is owned by Derbyshire County Council (as an aside, I have not managed to click anywhere on Drone Scene, using the Local Authority tool, that shows DCC).
In their response to Simon Hawkins’ FOI request, DCC fall back on the common Council “Parks and Pleasure Grounds” clause forbidding the use of model boats and aircraft.
The issue of whether these byelaws are actually enforceable has been discussed as infinitum in various threads on the forum, and, as ever, people’s experiences vary.
See further discussion here: