The 19-year-old Sarnian clocked a new personal best of 47.40sec. to pip David Hall in a cracking race to break his own island under-20 record and become the second fastest Guernsey athlete of all time over 400m indoors behind Dale Garland.
The time also makes Chalmers the fifth fastest British junior of all time and places him second on the European U20 list for 2016, just behind Victor Coroller of France who has run 47.34.
Chalmers was the fastest qualifier for the final having run a PB of 47.69 in the semi-final.
