JavaScript
The events calendar on the Museum of London and Museum in Docklands website uses a computer language called JavaScript.
In theory, JavaScript can be used for dubious purposes. Naturally the Museum are not using it in this way, but some computers (for example, those used on office networks) have JavaScript turned off as a security measure.
Unfortunately, this means the events calendar will not work on such computers. However, you can still search for events on the events listing pages using the ‘back’ arrow icon and ‘forward’ arrow icon to select the desired date.