With respect, smiles, I think it is possible you may have been mistaken about finding Black Lake Cottage. If, like me a few years ago, you saw a dwelling with the name 'Black Lake Cottage', I'm afraid you were looking at the wrong building. This particular building was, in Barrie's time, a pair of attached cottages known as 'Black Lake', and one of them housed the Lamport family, of which two young sisters worked as domestic servants at the original Black Lake Cottage before the Barries took it over. One of them, Alice, continued to work there, as an assistant to my grandmother who was Barrie's housekeeper there.
To find Barrie's Black Lake Cottage you need to go down Tilford Road (ie. towards Tilford) a few hundred metres on the same side of the road. Long before Barrie's time there it, too, had originally been two attached cottages. When Mary Barrie bought the lease it was already one large-ish dwelling, and over the eighteen or so years that she lived there (nine years intermittently with James, and nine years continuously with Gilbert Cannan) she had it modified and enlarged. It was further enlarged, modified and subdivided over the intervening years and the present whole structure comprises three dwellings. You can forget about the third of these - the part farthest from the road (which was built over part of the garden) - but the other two are roughly two halves of what was the Barries' dwelling. Their present names are: 'Barrie House' (essentially the front portion of the Barries' cottage), and 'Lobswood House' (the rear portion), and they are approached via a shared access and parking area. There has never been a closed gate there whenever I have passed by or visited.