Go without a plan.
For in a city with a myriad of opportunities it is impossible to choose anything to do when put on the spot.
One other thing you should never do in London.
Go when it's pissing it down with rain.
For in a city which is mired in a blanket of grey and misery it is even more impossible to choose anything to do when put on the spot.
Instead you will find yourself being pulled into the Tate Modern even though you know you're going to hate it because you're just not a fan of modern art and even thought you know that your significant other is going to hate it too.
It's ok though, you last about 20 minutes in there. The breaking point is when your significant other sees a piece of art which is some wood with stones hanging from it at varying lengths. It turns out that that is his limit when it comes to modern art.
You swallow your "I told you so" and trudge back outside into the gloom (after a visit to the gift shop).
This is why it's important to have a plan.
Instead of heading aimlessly over the Millennium Bridge towards the comforting glow of St Paul's Cathedral you head over it with purpose, laughing at the pigeons sat in rows, laughing at the fact that your hood is so big you can't actually see out of it and laughing at the fact that thanks to the wonder of Twitter and The Cafe Cat you know exactly where you're heading.
Responding to my plea for somewhere cool to have tea and cake she gave me more than one idea and one h happened to be close by to us, underneath the menacing clouds.
For we are headed to Bea's of Bloomsbury (the St Paul's branch).
We follow the directions on the website (when they say keep turning right they really do mean keep turning right) looking for the hanging teapot lights, foolishly thinking they're hanging on the outside. At the point where I'm about to lose my temper and the rain is really starting to wear us down, we spy a welcoming glow in the distance...
What better way to decorate a tea shop than with hanging teapot lights?
Bea's of Bloomsburys manages to do a difficult thing - be homely without being chintzy, be small without being claustrophobic and be cosy whilst still maintaining a sense of 'coolness'.
We sit and we talk and we do that ever so British thing of rolling our eyes at a table of women who shriek at some unexpected news. We talk about the weekend ahead, which is going to be spent in Horsham, staying with some of The Person's family and we talk about this and that and a little of the other.
And then we decide to just head to the pub where we're meeting his family later.
Because we are in London without a plan.
And that's just fine.