Quote:the Henley house was undeniably modest in size, and ghostly quiet.
Note definite article 'the' before Henley and lower case 'h' at the start of 'house'.
The Henley house: a house, previously referred to, located in Henley, or possibly owned, inhabited, designed or built by an individual or organisation called Henley. Which of these is the case will be indicated by the context.
A Henley house: an unspecified house located in Henley or or possibly owned, inhabited, designed or built by an individual or organisation called Henley. Which of these is the case will be indicated by the context.
Henley House: could be the name of a building which could be located anywhere. Also it is the name of the first inland post established by the Hudson's Bay Company, and of numerous buildings, companies etc, in the United Kingdom and elsewhere.