Вот заполненные пропуски A–F:
A – 2. that was firmly established in this race.
B – 5. when they studied together at Harrow School.
C – 1. that's why local taverns and accommodation were fully booked.
D – 7. that Oxford won the race "easily".
E – 6. that the race is held.
F – 4. who were not initially allowed to take part.
Лишняя часть: 3. while they race from Putney to Mortlake on the River Thames.
Таким образом, получаем последовательность: 2, 5, 1, 7, 6, 4.