This garden is depicted on the Second Edition Ordnance Survey 25-inch map of Anglesey XV, sheet 6 (1900). Its main elements on that map include greenhouse, kennels, flagstaff, terrace, orchard, carriage drive, conservatory and summerhouse. C.H. Nicholas. RCAHMW. 7th August 2006.

Cornelyn was built in 1861 by local masons, for William Massey, a barrister from Cheshire who practiced in London. It remained in the family until 1960. A gasometer was marked on the 1889 to 1959 OS maps, at buildings referred to as Ffynnon Lydan, indicating a private gasworks which would have lit the house and estate.