The following information might be useful for anyone researching theatre in London, or for anyone interested in theatre and theatre studies :
https://www.londontheatre1.com/reviews offers reviews of London West End and Off West End productions from 2011 onwards. There are probably 500 reviews between 2011 and 2014. Last year, however, was a growth year in terms of the productions being reviewed. They have now 50 reviewers and there were over 850 productions reviewed in 2015 alone, in and around London – in the West End and Off West End.
The year 2015 reviews are now also available for free in PDF at https://www.londontheatre1.com/2015-Reviews-londontheatre1.pdf