The next recorded owner of Wavertree Grange was Samuel Robert Graves. The 1851 Census lists him as an Irish-born 32-year-old "Commission Merchant", living in Falkner Square, Liverpool, with his wife, 2 young sons and 4 servants. By 1853 (Gore's Directory) he was at "The Grange, Cow lane, Wavertree" with an office in Redcross Street, Liverpool. The 1861 Census describes him as "Mayor of Liverpool and Ship Owner", living in Cow Lane with his wife, 3 sons, 2 daughters and 5 servants (plus a coachman next door). It was Graves who in June 1866, as Liverpool's Member of Parliament, accommodated Queen Victoria's second son, Prince Alfred, Duke of Edinburgh, in his home while the Prince was on a Royal Visit to Liverpool; and it was in honour of that visit that Cow Lane was renamed. The Liverpool Mercury reported that "Mr Graves's residence, The Grange, is an unpretending edifice … approached by a thoroughfare which has hitherto been known by the undignified appellation of Cow-lane, but which will henceforward bear the title of Prince Alfred's-road".

Sadly, Samuel Graves died of a heart attack in January 1873 at the Euston Hotel, London. He was a well-respected M.P., and the "enormous line" of about 300 mourners' carriages is said to have taken half an hour to pass the Grange on its way to Toxteth Park Cemetery in Smithdown Road. At the 1871 Census, Graves had been listed as "Merchant & Member of Parliament" (at "Grange House, Prince Alfred Road") with his wife, 2 sons, 1 daughter and 6 servants, but in 1881 the occupants (at "8 Prince Alfred Road") were Elizabeth Graves (widow), her 3 sons, 1 grand-daughter and 6 servants. At the next Census, 1891, the house ("Prince Alfred Road The Grange") was described as "To let - a person in charge"; and by 1895 it had been demolished.

The assumption, at this time, would have been that terraced houses would soon cover the site, which is what had happened in the case of similar 'gentlemen's residences' on the edge of the village of Wavertree as the built-up area of Liverpool expanded. Suddenly, however, it was announced that the estate was among 108 acres of land which had been acquired by an anonymous individual, and which was now being re-landscaped and gifted to the City of Liverpool as "the Children's Playground". Officially it became Wavertree Playground, unofficially 'The Mystery' - or 'The Mizzy'. But that's another story …