Then you saw a different show.
Certainly he came under criticism from other pannelists, so what? They didn't talk him down and run their yap nonstop. He did. For the 30 minutes I watched, which was immigration, which gets raised every week. He continued his nonsense about 480 odd million europeans queuing at the door to take YOUR jobs and refused, as usual, to listen to facts or reason. If you mean by barracking that Chuka Umuna criticised him for his 'foreign languages I heard on trains' comment, or whatever the fuck he said, then that was well deserved criticism, which was far from barracking - and it was met by a mealy mouthed straw man. As usual.
Ukip are on almost every week now, they were on last week as well. I can't remember the last time Caroline Lucas was on, not for many months I think. TUSC haven't been on iirc, nor the Socialist Party, or even the SWP.