My wife and I have created Dress Circle.
The idea behind Dress Circle came from a Google Doc I've had for years with every show (Play, Musical, Opera) I've seen in ranked order, eventually we translated it into a webpage (https://www.dresscircle.co.uk/+thehodge) so others could view it and then friends wanted their own list.
To enable features such as alerts and showcases, we started to build a database Theatres in the UK then we added the shows that were in them and THEN we added the actors (and creative teams).
Then we started to add historical productions and.. well here we are, we've accidentally built IMDB for UK Theatre
(I thought with the timezone this might be a good time to post)