Was looking at the scorebook for Bannerman's famous innings on Charles Davis's site the other day, and his scoring rate (and that of his partners) is quite unusual.
After 50 (4-ball) overs, he'd scored 45 off 100 balls - a reasonable rate by modern standards, but with only one 4 - out of 67-3.
He then added just 2 more singles off the next 43 balls he faced; with 5 runs from Cooper and an extra, he now had 47 out of 75-3.
Then after hitting a 4 off Ulyett to reach his 50, he apparently went berserk, scoring 52 off 42 balls, including 10 fours, to reach 99 out of 135-4 (just 6 runs at the other end, plus 2 more extras).
He continued to score at a reasonable rate for the rest of the day, adding another 27 off 48 balls, while his partners managed just another 4, so he was then 126* out of 166-6.
Finally, at the start of day 2 he scored a more sedate 39 off 99 balls and was almost matched by his partners, who added another 30 (plus 5 extras). At this point, Bannerman retires on 165 out of 240-7.
So his record proportion of 67.3% was largely due to that period in the middle where he scored 79 out of 91, a whopping 86.8%.