I have no connection, but, the Peter SLADER who married Wilmott PURCHASE was born ca 1798 and was probably an uncle to the Peter SLADER you have found. He died in 1875 and probate shows his wife Willmett (sic) was executrix. The 1818 Peter SLADER was the son of William & Margaret SLADER, and was shown as the unmarried son of a farmer in both the 1841 and 1851 censuses.