See, if we lived in L.A., it would be easy to alternate outings to the park with days on the beach, happy in the knowledge that a rainy day would be a very rare occasion to stay in an watch a movie or bake cookies. In London however, rainy days are the rule, not the exception, and parents have to find outlets for their little monsters' energy!
Thankfully I'm not the first person to think of this problem and a lot of places have been created with exactly this in mind... The Kids Zone at the National Army Museum is a large indoor play area for 0-8 years old, with a climbing castle, some slides, a couple of rocking horses, and lots of soft play pads for little ones to roam freely. We visited over the bank holiday week-end, and Monsieur Baby loved everything, even climbing into the castle (with Hubby Dearest following diligently to make sure he didn't get trampled by bigger kids!) at some point!
Open all days, this play zone is created around family needs and is a truly wonderful place to stop in the middle of a busy afternoon shopping on the King's Road when the little ones need to come out of the buggy for an hour. It was a bit counter-intuitive for me to go there seeing as I don't approve of guns, armies, and generally anything related to warfare, but we had a great time overall, and will very likely come back! By the way the above picture is from the website and depicts the old-style kids zone, it's been remodeled and has now full padding on the floor and walls and new play zones with climbing walls and slides. (I didn't want to take any pictures seeing as there were so many children playing around and I like to protect their privacy.)
Days are divided into 50-minute slots that you can book tickets for up to three days in advance, with no more than 30 tickets sold for each time-slot, ensuring that it never gets too crowded... It's important to book in advance, according to the staff all tickets for the same day get sold out by 11am. I found that 50 minutes was plenty for my little munchkin, he eventually got a bit hyped-out by 40 minutes, so we left a bit early, but then again he is only little...
Book your tickets here (£2.50 per child over 6 months, adults enter for free) and don't forget the area can be booked for a birthday!