Throughout the EU referendum campaign, a recurring theme has been that the Remain side lacks "passion". Not tonight. At the BBC's Wembley Arena debate, the triumvirate of Sadiq Khan, Ruth Davidson and Frances O'Grady gave the pro-EU side the punch it has lacked. They remorselessly pummelled Leave's unchanged line-up of Boris Johnson, Gisela Stuart and Andrea Leadsom over their campaign's mendacity.

O'Grady spoke with the authority of a TUC general secretary, representing more than six million workers ("If you don't believe the experts, listen to the shop floor"). But it was Khan and Davidson, battle-hardened from their respective campaigns (London mayoral and Scottish referendum), who were the stand-out performers. While avoiding crudely personalised attacks on Johnson they relentlessly exposed his inconsistencies. When Khan called his mayoral predecessor out on the "big fat lie" that Turkey is set to join the EU, Johnson wore the smirk of a man who knows he is dissembling. The loudest applause of the night came when Khan brandished the Leave campaign's infamous immigration leaflet and denounced it as "Project Hate". His energy, nearly 19 hours into a Ramadan fast, was remarkable.

Though the Leave side again excelled at message discipline, urging voters to "take back control" at every opportunity, they committed two notable gaffes. First, Leadsom refused to pledge to return a £600,000 donation from a former BNP member. Then Stuart was caught out when asked how much Leave would reduce immigration by. "What we said is we would take back control," she helplessly pleaded. Johnson was on stronger ground, sticking tightly to Leave's script and ending with the rallying cry to make this Thursday "independence day".

Remain lacks a slogan to rival "take back control" but Khan and Davidson hammered its closing message that withdrawal would be "irreversible" (one strategists say polls strongly) and its defining theme that Leave "has no plan". Though the pro-EU side's strongest suit remains the economy, two of its most potent interventions came on security. Khan recalled how the European Arrest Warrant enabled the deportation of one of the 21 July London bombers from Italy. In an extended peroration, Davidson declared: "The other side have said throughout this debate that they don't like experts but when it comes to keeping our country safe and secure I want to listen to the experts. So when the head of GCHQ says we are safer in the EU I listen. When five former NATO chiefs say we are safer in the EU I listen. When the head of Europol who is a Brit says we are safer in the EU I listen. When the head of MI5 and MI6 says we are safer in the EU I listen."

Few minds will have been changed by tonight's debate. The relentless claims and counter-claims are only likely to have left the undecided even more perplexed. But Stuart unwittingly revealed what could be Leave's fatal weakness when she asked at the opening: "If we were not in the EU would we join it?" The problem for Leave is that we are. For the unpersuaded, the status quo is always the safest option. "Trust us and it'll all be fine, that's not good enough," said Davidson. "If you vote to go on Thursday, you cannot change your mind on Friday." It is the risk aversion of the British electorate that will likely deliver Remain victory. But tonight Khan and Davidson supplied pugnacity, too.