You can wear whatever you like when exploring London but you might want to consider a few things before you begin your day's exploration. The first thing to say is that London's weather can be unpredictable so prepare for anything, regardless of the time of the year you are visiting.
Comfort is the key with any serious walking. Pay careful attention to your footwear. You may feel the need for walking boots, maybe a sports shoe or perhaps a pair of loafers that you alone, find particularly agreeable.
All sounds fairly obvious?
Absolutely; but how often have you visited or toured somewhere new and been surrounded by inappropriately dressed newcomers? Exactly...
A weather-proof jacket will keep you dry and protect you from the wind. A rucksack/backpack is also a good idea. It is somewhere where you can keep extra layers, an umbrella, a bottle of water etc. Don't forget your sunglasses, any medication and your camera/phone. Keep your wallet and any important documentation on your person.
And if that all sounds just a little too utilitarian for the ladies; all I can say is accessorize, accessorize, accessorize!
On the other hand, if you are planning a shorter and less arduous assault on the city - say a walk through Mayfair - you may want to up your game. When you stroll down the Burlington Arcade you will almost certainly want to look your best.