This is an unusual English surname. It appears to be locational, but no such place as Westcar appears in any of the known gazetters of the past centuries. That in itself is not uncommon, as an estimated three thousand surnames of the British Isles do originate from now "lost" medieval places, of which the only memory in the 20th century is the surviving surname itself. What makes it makes this name more unusual is that the spelling appears to have no meaning, or at least the known spelling has no obvious correlation, unless it be to somewhere like West Carne, which translates as the rocky mound to the west, a hamlet in the county of Cornwall. We have no evidence that the surname does originate from Cornwall, but clearly it must come from somewhere. Thre greatest concentration of recordings appears to be in the diocese of Greater London. This is quite normal as through the ages when people in Britain left their original homes, they usually headed for the capital cities of which London was the largest and best known, offering the greatest opportunities. In this case we have recordings from as far back as 1685 when Susanna Westcar marrried Hugh Strang at St James church, Dukes Place, Westminster on August 6th of that year, Henry Westcar who married Anne Sharratt at St Ann's Soho, on June 9th 1753, and Jane Westcar, who married James South, also at St Ann's soho, on August 7th 1822.