Robert wrote:
It started and ran perfectly for the first 3 cuts of the year but the
4.5hp Honda has played up this evening. It started without problem, ran
for one to three minutes, backfired then stalled. Tried it five times,
same result.
Grateful for any suggestions.

Try unscrewing the curberettor float boal, and giving it a clean. It
is possible that some bits of muck are being sucked up and blocking
a jet. Blow through the jet from inside the carb. as well, you could
use a garage air line, or possibly a foot pump.