This is a hit song from the 1920s, which has been much used in stage musicals, films and television series over the years.
The organ is a hybrid theatre organ combining ranks from the Redford Barton 3/10 and the Wyton House Compton 4/16, hence the name Brompton, which is also the name of a fashionable district in London. Barton organs are famous for their sweet sound - they were known as the 'golden voiced Bartons'. The addition of Compton ranks adds body and dynamism to the organ while maintaining sympathy with the original sound style.