Newbury Park Brick Structure

I've always assumed that buildings of that style were associated with traction current supplies. There are several such buildings dotted around the network. Referring to the yellow peril for Newbury Park I find that there was a traction switch house located more or less where the brick building you describe is located. I suspect that this must be what the building is. The traction switch house was provided in connection with the long gone car sidings and allowed them to be fed from either the inner rail or from a direct feed from Newbury Park substation. The switch house also contained the circuit breaker for the sidings, which was effective regardless of which supply was used. Presumably it was the presence of the circuit breaker which necessitated a full blown brick structure, rather than the more usual changeover switches in yellow boxes.