The age for adults in the 1841 census is rounded down to the nearest 5, so if Robert Laurie was age 60 in that census, he could have been aged from 60 to 64. Also the census was taken in June. So he would have been born somewhere between 1776 and 1781 - - providing, of course, he knew exactly how old he was! The death you've found gives a birth date of about 1771, but the age given at death is only what someone at the time said they thought it was.
A death in Scotland in 1843 won't have a death certificate as they didn't come in until 1855. Is the death entry your found a burial entry in a parish register?
On FamilySearch there are a few births of a John Laurie or Lawrie or Lowrie or Lourie in the right time frame, but difficult to know which it might have been, if it was any of them.
Was William is only or eldest son? If he was, there's a good chance Robert's father would have been called William (use of Scoottish naming pattern). Not infallible but can be useful.
