Thanks for writing. Cooke's reference to Wagner seems strangely ill-considered for so sagacious a musical thinker. What does 'Fidelio' do? What does the 'Matthew Passion' do? Cooke undoubtedly knew both works very well  as, equally undoubtedly, did Mahler  yet he forgets their 'progressive tonality'...

The publisher of the booklet seems to be the Royal Liverpool Philharmonic Society.