You can drive in from the backside of the hotel Hyatt Regency London - The Churchill.
It is a narrow alley where there is a basement parking with a iron gate in front. the first Hour is only free and after that 6 Pounds per hour.
I arrived 3 in the morning and the hotel personal was not aware of the existence of the charger.... But after couple of calls i got in.
Parking skills required the garage is narrow!!!! The charger is in the far left and you have to take several curves to get the car on its spot. i think when spot 41 is taken it becomes a bigger challenge.