The right hand bit is the original house, the left hand bit is the extension!
"Although the original house at Pensychnant (the lower, right-hand end) was built about 1690, the main house, and really the whole character of the estate dates from the Victorian era. Built between 1877 and 1882, Pensychnant was the country-home of Abraham Henthorn Stott, architect of the Lancashire cotton mills. Stott & Sons was one of the most eminent Victorian firms, building about a fifth of the mills in Oldham at a time when Oldham did one eighth of the spinning in the world. By 1937, the cotton industry had collapsed and Pensychnant was sold, but in 1967 Brian Henthorn Stott, great grandson of the architect, bought it back again. Now, the Pensychnant Foundation continues in his memory."
The Pensychnant Estate is well worth a visit, it's at the top of the Sychnant Pass. It is mainly a nature reserve and its owned by a small charity who are always struggling to keep it going.
http://www.pensychnant.co.uk/