An avalanche in British politics?
The 11 MPs will operate as a parliamentary faction, seek new MPs, and then establish a party. The TIGers already equal the Liberal Democrats and if TIG exceeds the 36 MPs in the Scottish National Party contingent it can claim third party status and be automatically called in Prime Ministers Questions.
The Conservatives quit mainly over Brexit and the reasons for former Labour MPs leaving their political tribe are for them summarised in two words: Jeremy Corbyn, the Labour Leader. Luciana Berger has endured a vile campaign of anti-Semitism and says that Labour is institutionally anti-Semitic. Mike Gapes highlighted Corbyn's threat to national security, as did Ian Austin, the Labour MP who didn't join TIG. Both men have visited the Kurdistan Region.
The former Labour MPs looked pained and sad at the launch of TIG but free at last while efforts by Corbyn supporters to tarnish them only proved their point. Most significantly, Labour Deputy Leader, Tom Watson, said "good colleagues" had come to "a premature conclusion," essentially victims not villains. The MPs' dramatic departure marks a growing realisation that a hard-left Labour party is either beyond, or nearly beyond redemption.
Some of Corbyn's supporters are less concerned about him than keeping his radical economic programme. Corbyn is no longer a novelty and his personal leadership ratings are astonishingly bad.
The departed Labourites are the collective equivalent of the boy who told the Emperor that he had no clothes and may have opened a small hole in the dam: TIG initially attracted 14% in one opinion poll and has, in the jargon, landed with public opinion.
My guess is there will be few more Conservative defections but there could be more from Labour. So much depends on how Brexit resolved, if there is an early election or a new referendum, or both, and if Labour MPs can win major internal change.
Some Corbyn supporters claimed that the defectors were most concerned about Labour's left-wing economic policies. Labour MPs are often less enthusiastic about them but the bigger division concerns foreign and security policy. Many were shocked by Corbyn's reaction to Russia's lethal use of a chemical weapon on UK streets and his suggestion that the chemical virus be given to Russia so it could check if it was theirs or not. Russia was clearly culpable and Corbyn wisely retreated.
Labour loyalists often argue that Prime Minister Corbyn would be constrained by moderate ministers and MPs. But key decisions are often taken rapidly by the few in emergencies and where deep instincts matter more. A weak reaction to a Russian invasion of Estonia could bust Nato. Given Corbyn's refusal to support the use of the RAF in defeating Daesh in either Iraq or Syria, what could the Kurds expect in any future emergency?
That Corbyn could become Prime Minister drives an urgency in those who have left and among moderates who say people should stay and fight within the Labour Party. TIG could be cathartic for those who believe the Labour brand, its voting base, and property can be saved. There is, therefore, in practice a twin-track strategy to catalyse change.
TIG seeks to build a centrist party that can only prosper within a proportional representation system of voting but the beneficiaries of the current first past the post system will block that, and only a referendum could secure electoral reform.
Labour Leader Harold Wilson famously said that a week is a long time in politics and that applied in spades last week. Commentators are divided between those who intuit that the breakaway group could be a significant disrupter and those who think the main parties can absorb the blows after Brexit with a new Conservative leader and with Corbyn maybe giving way to a fresh face and/or Labour decisively reforming its policies and behaviour. The TIGers may have fired a starting gun last week that begins an avalanche but it's an open question as to who will be suffocated or survive.
