You're talking about walking out of May's meeting with opposition leaders? That wasn't an own goal, it was Vince Cable playing as the 12th man for the Tories. 1) The meeting could not have been about significant business because Umunna and Soubry were there; as they are not party leaders, they don't have the necessary clearances. 2) Apparently Chuka was not actually invited and just tagged along with Soubry. He was allowed in because of … 3) The meeting wasn't a discussion. May just brought all the senior opposition figures in so she could rant at them for not supporting her deal. Incidentally, it's reported that Cable also walked out. Not a good look for the leader of the party that says it wants Brexit stopped, which is probably why he forgot to mention it while he was attacking Corbyn and defending May as she went full Downfall meme. As ever, scratch a liberal and a fascist bleeds.