The British Olympic Association won a $100,000 grant from the IOC'S Olympic Solidarity World Programme on Thursday as they prepare for the final Sochi 2014 qualifying tournament.
However following swiftly on from that has come the decision from Longstaff, who was part of the 32-strong preliminary squad for the final Olympic qualifier, to call it quits internationally.
The 38-year-old has 101 caps for his country, earning his 100th in the Olympic pre-qualifying tournament in November that Britain won to book a trip to Latvia next month.
Longstaff got his first taste of senior competitive action at the 1994 Pool A World Championship and is wishing Britain the best of luck in their attempt to secure a place at the Sochi 2014 Olympics.
Britain were last represented in ice hockey at the 1948 Olympics in St Moritz and Longstaff, who plays for the Guildford Flames, said: "I would like to wish all the guys the best of luck in Latvia and I will be rooting for them back home.
"I am proud that the last game I played for Great Britain helped them reach the final stages of qualifying for the 2014 Olympics.
"It has been a tremendous honour to play for the Great Britain national side. I have so many proud and happy memories, right back from making my debut against Russia in Pool A back in 1994.
"I have played with so many great teammates, too many to mention, but they have all played a part in my Great Britain career."
And Great Britain head coach Tony Hand, who will name his final 22-man squad for the Olympic qualifying tournament on Saturday, paid tribute to Longstaff's services.
"David has been a terrific player in the Great Britain set-up for the last 18 years," he said. "I remember him as young kid in the Great Britain squad and he matured into a true leader on and off the ice for the national side.
"To play in 17 major tournaments show how talented Lobby is and he has achieved so much nationally and internationally.
"He has been a popular figure in the Great Britain dressing room for years and years and he will be sadly missed.
"I would like to place on record my thanks for what David has done for the Great Britain national side. He has been a credit to his country."
- Sports & Recreation
- Great Britain