At the end of 1965 Mike Hailwood left MV to rejoin Honda, and the stage was set for one of the great years of TT racing in 1966, which was postponed until September because of a seamen's strike.
The Senior was the time British enthusiasts had witnessed the Hailwood/Honda - Agostini/MV battle at first hand, and they were not disappointed.
The 500cc four-cylinder Honda was a brute and not the ideal machine for the Mountain Circuit, but Mike tamed it with a display of skill and bravery that was the hallmark of a true champion.
A lap record gave the first round to Hailwood, but 'Ago' was equally determined to stay in the hunt, and on the second lap he bettered Mike's effort to keep the Honda in sight. Hailwood increased the record to 107.07mph on lap three to lead his great rival by 13 seconds. He then gradually pulled away to secure his ninth TT victory and perhaps his most impressive. Agostini was a brilliant second, with RAF corporal Chris Conn completing a splendid week by finishing third on his Norton.
Hailwood and Agostini had met earlier in the week in the six-lap Junior, the Italian winning his first TT. The struggle lasted just a few miles until Hailwood's Honda ground to a halt at Bishopscourt on the very first lap, leaving the way clear for Agostini and the MV.
That didn't stop him setting a new record on his second lap of 103.09mph en route to a comfortable victory over the AJS of Peter Williams and the impressive Norton mounted Conn.
Hailwood returned to the Lightweight race armed with the fearsome six-cylinder Honda, a combination nobody else could get near. Both Hailwood and Yamaha's Phil Read broke lap record from a standing start, with Hailwood leading by 39 seconds.
Read retired on the second lap at Ginger Hall and his teammate Bill Ivy took over second spot from Hailwood's teammate Stuart Graham. Both Ivy and Graham hit problems, however. Bill eventually retired, but Graham continued after having trouble restarting his Honda at his fuel stop. Hailwood won with nearly six minutes to spare from Graham, with development engineer Peter Inchley third on his Villiers single cylinder two stroke.
Yamaha gained ample revenge over Honda with a stunning display in the three-lap 125cc race, with Ivy and Read in record-breaking form. The race was delayed because of mist on the Mountain, but once underway the V4 Yamahas destroyed the opposition. Read led at the end of the opening lap but Ivy, with two record laps, beat his team mate - and later bitter rival - Read, with Hugh Anderson trailing in third place on the square four Suzuki.
Support for the 50cc race continued to decline, although Taveri and Bryans engaged in a wheel-to-wheel struggle from the massed start, with Bryans setting a new lap record of 86.49mph on his way to his first TT victory.
It was even closer in the three-lap Sidecar race, with BMW aces Fritz Scheidegger (with English passenger John Robinson) and Max Deubel separated by just four-fifths of a second at the finish. Although Scheidegger held that slim advantage, he was excluded from the results because of an alleged fuel irregularity. However, he appealed to the FIM twice and was eventually declared the winner.