I could never make out whether he wanted to goad his son into leaving him, in order that he might drink himself to death in peace, or whether he merely indulged in his natural love of tormenting, valuing Derrick's devotion as conducive to his own comfort, and knowing that hard words would not drive him from what he deemed to be his duty.

I rather incline to the latter view, but the old Major was always an enigma to me; nor can I to this day make out his raison-d'etre, except on the theory that the training of a novelist required a course of slow torture, and that the old man was sent into the world to be a sort of thorn in the flesh of Derrick.
What with the disappointment about his first book, and the difficulty of writing his second, the fierce craving for Freda's presence, the struggle not to allow his admiration for Lawrence's bravery to become poisoned by envy under the influence of the Major's incessant attacks, Derrick had just then a hard time of it.

He never complained, but I noticed a great change in him; his melancholy increased, his flashes of humour and merriment became fewer and fewer--I began to be afraid that he would break down.
"For God's sake!" I exclaimed one evening when left alone with the Doctor after an evening of whist, "do order the Major to London.

Derrick has been mewed up here with him for nearly two years, and I don't think he can stand it much longer." So the Doctor kindly contrived to advise the Major to consult a well-known London physician, and to spend a fortnight in town, further suggesting that a month at Ben Rhydding might be enjoyable before settling down at Bath again for the winter.

Luckily the Major took to the idea, and just as Lawrence returned from the war Derrick and his father arrived in town.