It's the Free Trade Hall! The seating plan is in the papers of the Northern School of Music as it negotiates with local authorities and the Royal Manchester College of Music, what the new RNCM would look like. Its facilities included a concert hall and this seating plan could have been some inspiration.
Do you remember attending concerts at the Free Trade Hall? What was the best seat?
Date is totally a guess.
Part of the #NSM2020 project "A 20/20 Legacy: the centenary of the Northern School of Music" supported by the National Lottery Heritage Fund.