The most famous of all his matches was that between his Sancho and Lord Darlington's Pavilion. There were really three matches. In the New Claret Stakes at the Newmarket first Spring Meeting, 1805, Pavilion beat Sancho and some other horses (6 to 4 Sancho, 7 to 1 Pavilion). Mellish then challenged Lord Darlington, and a match was run in the summer at Lewes—four miles for three thousand guineas, Buckle riding Sancho and Chifney Pavilion. Sancho (the non-favourite, 2 to 1) won easily. Another match was run over the same distance on the same course for two thousand guineas, 6 to 4 on Sancho, who broke down badly. Mellish on this occasion lost altogether five thousand guineas, though at one moment before the race he had been offered twelve hundred to have it off. A third match for two thousand guineas over a mile at Brighton was made in the same year, but Sancho had to pay forfeit. Colonel Mellish's colours were white with crimson sleeves. His trainer was Bartle Atkinson, who from the time of entering his service in 1802, till 1807, turned out what was probably a greater number of winners than any other private trainer for one owner has ever done in the same period of time. In 1804 and 1805 he won the St. Leger with Sancho and Staveley, and trained many winners besides. In spite of all these successes, racing proved most disastrous to the Colonel's fortune, and like the vast majority of racing-men of this stamp, he left the Turf a ruined man. In his palmy days it is said that he never opened his mouth to make a bet under £500.

He wanted to be everything at once, and as the saying went, he was "at all in the ring"; till by deep play, by racing and expenses of every kind, and in every place, he found it necessary to part with his estate in order to satisfy the demands which obsessed him on all sides.

Though the most popular of men, Colonel Mellish once had a serious altercation with the Honourable Martin Hawke, and the result was a duel, when the following conversation is said to have occurred—it shows the light-hearted spirit of the combatants.

Mellish. "Take care of yourself, Hawke, for by —— I shall hit you."

Hawke. "I will, my lad, and let me recommend you to take care of your own canister!"

The seconds, on hearing this, agreed that they should not take aim, but fire by signal, which was done. The Colonel missed, but Hawke's shot took effect, by passing round the rim of his opponent's stomach, and eventually penetrating his left arm; on which Mellish exclaimed, "Hawke, you have winged me! Lend me your neckcloth to tie up the broken pinion!" This was immediately complied with, and the arm being bound up, they both returned in the same chaise, as good friends as ever!

This duel was fought in 1807 in a field by the roadside, and originated in a quarrel about the Yorkshire election, from which both duellists were returning in their drags.

Mellish would appear to have run a great risk of being killed, for the Honourable Martin Hawke was a singularly gifted man and could do incredible things with a pistol. Indeed his skill in that direction was probably never equalled. His nerve and courage were of the highest order.

Mr. Hawke once fought a duel near Brussels with a certain Baron Smieten. Whilst the seconds were measuring out the distance, he amused himself by drawing a mail-coach with his stick on the bank of a sandy ditch. One of the seconds, a guardsman, came up just as the finishing touches were being put to the coachman's whip, and said "All's ready," to which Hawke replied, "Just let me put the lash to this fellow's whip." Having touched off this, he instantly proceeded to touch up his antagonist, mentioning that as he had put him to so much trouble (they fought over the frontiers) he must give him a touch, but would content himself with spoiling his waltzing for a little; naming where and how he would operate—and this he did to a hairbreadth.

At one time the patron of all the superior pugilists, Colonel Mellish first brought many of them into notice. He arranged the first battle ever fought by the famous Tom Cribb, who was matched by the Colonel against Nicholl, who beat him. Unfortunately for his gallant backer, Cribb on this occasion entered the ring very drunk, and, of course, fell an easy prey to an antagonist whom in future days the champion of England would have beaten in ten minutes. Colonel Mellish likewise made the match betwixt Gully and the Game Chicken; the former of whom he caused to "give in," much against his inclination. The Colonel's humanity on this occasion cost him a large sum, as he had backed Gully heavily. Nevertheless, he insisted upon his yielding, the man being reduced to such a state of weakness that his supporter was afraid of an accidental blow proving fatal.