http://trove.nla.gov.au/ndp/del/article/12926500 23 April 1851 SMH
On the 15th instant, at Murrurundi, New South Wales, Charles Henry Hallett, Esq.,
M.R.C.S., London, aged 26 years, eldest son of John Hallett, Esq.,
M.R.C.S.L., of Devonport, England — late Demonstrator of Anatomy at the University of Edinburgh.
So the newspaper editors did not have a set protocol as to how to report this accreditation in NSW in the 1850's ...
Edit to add at the trove digitised newspapers online site .... try searching for MD MRCSL .... lots of results, not just Dr Benson ! to me that would be confirming he was NOT a quack, because I assure you SOME of the surnames from those NSW cuttings with MD MRCSL are also found on the NSW Medical Board list released Jan 1861, and some are not

HOWEVER I still do not see how the Dr Benson at Carcoar and the Dr Benson on the Chapman birth cert are ONE and the same person ... It is not an easy task to get from Kincumber NSW to Carcoar NSW even today, and it would be VERY difficult in the 1840's ... crossing the Hawkesbury, crossing the Nepean, crossing the Mountains, crossing the Macquarie, crossing the Belubula and all points inbetween...
PS, good summary Judith !
Cheers, JM