Can't make a reservation at the Farmer's Dog pub a month in advance. Is it really that popular?

My wife and I will be in London early August and so we wanted to book a lunch at the pub. It's literally July 1st, and no matter what date in August I tried, the website keeps saying "no times available". Is it that insanely popular that the moment August booking opened on July 1st, it gets filled up for the entire month? Or is the website just having a stroke?