(A) A private tutor The term is a pun on getting on fast. To get on fast you take a coach, you cannot get on fast without a private tutor —ergo, a private tutor is the coach you take in order that you may get on quickly. (University slang.)
“The books are expensive, and often a further expense is entailed by the necessity of securing `a coach.' ” —Stedman Oxford, chap. x. p. 188.
“What a dull, old-fashioned chap thou be st but thou wert always a slow-coach.” —Mrs. Gaskell: Cibbie Marsh (Era 2).