A top-secret blueprint of the D-Day landings could make £100,000 at auction this month. The rare World War Two document is believed to be one of only a few copies of the plan, codenamed 'Operation Overlord'.

A top-secret blueprint of the D-Day landings could make £100,000 at auction this month. The rare World War Two document is believed to be one of only a few copies of the plan, codenamed 'Operation Overlord'.