Filmed in England?
I'm unsure of where this was filmed. Many of the actors are British, but there are also Americans as well?
shareIMDb states the country as USA.
I know that one of the British actors in this film, Hugh Williams, was in the USA during 1930 with his wife, the actress Gwynne Whitby. The couple arrived back in the UK on 7th November 1930 on the 'Pacific Enterprise', having embarked at Los Angeles. There is also a record of the couple having crossed the border from Mexico into El Paso, Texas on 11th April 1930. They are also known to have departed Liverpool on 31st August 1929 on the 'Melita', bound for Montreal, Canada.
So although I can't say for certain that they were in the USA for the whole of 1930, it seems very likely that Hugh filmed Charley's Aunt while he was in the USA.