Stanmore raises the flag of Middlesex to mark Middlesex Day, which commemorates the day that the Middlesex Army regiment was entrusted to stop Napoleon's France advance into Portugal on May 16th in 1811. The conquering of Portugal would have resulted in the British being trapped in the Portuguese city of Albuhera with their backs to the sea in a similar situation to what occured in Dunkirk many years later. Fighting under the command of the Duke of Wellington, the Middlesex men fought ferociously to keep Napoleon's troops at bay to give Wellington and his troops sufficient time to re-trench. At the height of battle, the commanding officer of the young Middlesaxon fighters yelled “Die hard my men, die hard”. This expression led to the Middlesex Regiment becoming known as the Diehards (over 200 years earlier than the Bruce Willis character). Their Regimental badge is still inscribed the words 'Albuhera' in a similar way that 'Gibraltar' (also located on the Iberian peninsula) is inscribed on the Royal Marines badge.
The name 'Middlesex' comes from the Old English Middelseaxe, meaning the 'territory of the Middle Saxons' and was named after the Germanic tribes who settled in the area during the early Middle Ages and refers to the geographic location between the East Saxons (Essex) and West Saxons (Wessex). In this case, the 'sex' suffix of the three counties derives from seax, a traditional single-edged knife or sword used by the Anglo-Saxons, with both Middlesex and Essex adopting three seax swords as their coat of arms. Sussex shares the same suffix but is distinct from the other three counties as it was historically part of Wessex.
Now a historical and ceremonial county that Stanmore was located in, the county boundaries were defined by three rivers: the Thames in the south, the Lea to the east and the Colne to the west, and a line of hills forming its northern boundary with Hertfordshire. Its former area now lies almost entirely in the ceremonial county of Greater London, with smaller parts in the counties of Hertfordshire and Surrey. The county was the second smallest of the historic counties of England, after Rutland. The county ceased being an administrative county on April 1, 1965, with most of the historic county being absorbed into the newly created Greater London.
Today, the name lives on in the world of cricket with the Middlesex Cricket team who play their home games at Lord's and many people in Stanmore still include Middlesex on their address.
Further afield, there is still a county called Middlesex in Boston Massachusetts in the USA and I was surprised to discover that the central county of the three counties in Jamaica is named Middlesex (the others being Cornwall to the west and Surrey to the east) when I visited there last year.