Earliest References
The first reference to a person using the name is when one "Robert
De Clampytte", a merchant, was admitted as a freeman of the city
of Exeter
on 13 Feb 1331.
Robert De Clamputte (note the spelling has changed already!) shows up the next year, 1332, in the lay subs for Exeter.
A second person "Roger Atte Clampytte" shows up in the 1332
lay subs for Christow
(Cowick with Christow )
It should be noted that "De Clampytte" and Atte Clampytte", although grand sounding names, do not signify noble birth or high rank, "De" means simply "from" and "Atte" simply "At". However, the fact that they both appear in the lay subs and that Robert was made a freeman does signify that these two were probably a cut above the general run.
From the above it seems that we have one person living in (Atte) the Clampitt area and one living in Exeter but having come from (De) the area, it is reasonable to assume that they were related, as the population was small and travel restricted.
Another early reference to this name in England, is a record of the
christening of Abigael Clampit, the daughter of George Clampit which took
place on the 11th of August 1611 at Clyst
Saint George in Devonshire, research is ongoing and this name may
have been documented even earlier than the date indicated.
The earliest known reference in Ireland is recorded in a book "History
of Bandon" by G. E. Bennett about settlers arriving in 1585.
One of the settlers was a Clampett from Somerset.
Another early reference in Ireland,
is to James Clampett christened about 1700 at St John's in Limerick.