After a few days it occurred to me to go to the office of Mr. J.M.M. Baxter-the solicitor who had sold Holmescroft to M'Leod. I explained I had some notion of buying the place. Would he act for me in the matter? Mr. Baxter, a large, greyish, throaty-voiced man, showed no enthusiasm. “I sold it to Mr. M'Leod,” he said. “It 'ud scarcely do for me to start on the running-down tack now. But I can recommend-”
This is from "The House Surgeon" by Rudyard Kipling.
https://www.gutenberg.org/files/2381/2381-h/2381-h.htm#link2H_4_0016
I don't understand the meaning of "It 'ud scarcely do for me to start on the running-down tack now."
I am glad if someone would kindly teach me.