Animal welfare campaigner Bill Oddie has said it is "ridiculous" that fox hunting has been put back on the agenda as hundreds of demonstrators marched through London.
Prime Minister Theresa May has said she supports the outlawed activity and will renew a pledge to hold a free vote on overturning the ban.
Oddie compared the possibility of changing the law on fox hunting to changing speed limits just because "people like driving fast".
Speaking ahead of a rally and march through central London, Oddie told the Press Association: "I cannot believe that I'm standing here today saying to the Prime Minister this is ridiculous.
"It's a bit like some years ago they had a speed limit and they decided 'Speed limit? 30. On the motorways we'll go up to 60'.
"And then 15 years later somebody said 'Can we change it?' And they said 'Why?' - 'Well people like driving fast' ... We'll change the law for no sensible reason except purely there are people who want to go fox hunting."
Oddie said he believes Mrs May is facing "pressure from within" on the issue, adding: "The only people who actually want fox hunting to come back are not just people who do it or are connected with it, because there's all sorts of different levels, but it's the people who own enormous grounds and estates and that sort of thing."
He said: "For God's sake there's enough problems in this world to deal with and concentrate on them, and put this away once and for all. Shut up about it."
Hundreds of anti-fox hunting protesters made their way from Cavendish Square to Whitehall, with many wearing fox masks and holding signs saying "Theresa May for fox sake keep the ban".
Professor Andrew Knight, who is standing for the Animal Welfare Party against Mrs May in the constituency of Maidenhead, said it is "profoundly disturbing" that the Prime Minister thinks fox hunting is acceptable.
"We need to have leaders of our country that have basic compassion for animals and other vulnerable members of our society," he said.
"Theresa May clearly, I think, is unfit to lead this country, if she clearly and demonstrably lacks these basic qualities."
Meanwhile, he said he was "barred" from a hustings event in the constituency, saying that he was told the event was being restricted to a small number of the "more well known parties".
He said: "We think that that's completely unacceptable.
"Voters in that constituency deserve a choice and Theresa, if she's going to have policies that support blatant cruelty to animals, deserves to have her policies scrutinised and to be put on the spot by people like me there at the event."