It was the second closest finish in the history of the event, with Mark Baldwin's triumph on the Padgetts Honda in the1995 Ultra Lightweight TT race by 0.6 seconds over Mick Lofthouse the narrowest margin of victory ever recorded.
Speaking after a pulsating final lap that kept fans on the edge of their seats, an overwhelmed Anstey – a hugely popular winner on the Island – revealed his CBR600RR was beginning to run out of fuel in the closing miles, although he still lapped at 126.634mph.
“I wasn't sure I was going to make it over the line because I could feel the bike going – I can't believe it,” he said.
“I just kept my head down and went as fast as I could and I could see the times coming down and down.”
Anstey described the victory as his 'toughest' achievement since he made his TT debut ten years ago.
“I think that's the toughest one ever. I rode as hard as I could on that last lap.
“We had the bike on the dyno all week just trying to squeeze as much power out of it as we could because we knew it was going to be a really tight race.”
Johnson's demise gifted William Dunlop his first TT podium, with John McGuinness fourth, eight seconds behind Dunlop, and the top six completed by James Hillier and Ian Lougher.