At what was a pre-election conference in all but name, any time a group of Liberal Democrat activists gathered the same question would arise: how far can a buoyant party with a bounce in its step, a clear Brexit position and a new leader rise from its current 18 MPs?

The answer would generally range from a base assumption of 40 seats, rising to giddy speculation about 200 or more. At the top of the party there’s talk of plan “40, 40, 140”, in which strategists are banking on 40 winnable seats, a direct mail campaign to another 40 constituencies – possibly climbing to 140 should the party’s fortunes appear to be going particularly well. One MP even suggested the optimism was even more palpable than the days of Cleggmania.

However there was one point of consensus: amid so many political imponderables, a lot could change in the following few months.

Nonetheless, most of the Lib Dem faithful will return home from a sunny few days in Bournemouth energised for an election which could very conceivably end with Jo Swinson cast as the powerbroker in a hung parliament.

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Quite what Swinson would do with that power was the great unanswered question, as she has categorically ruled out supporting either Boris Johnson or Jeremy Corbyn in office, informally or otherwise. Beyond Brexit there is still a feeling among the party faithful that policy is a little thin.

The feelgood factor started early, as a pre-conference rally saw ex-Tory Sam Gyimah, unveiled as MP number 18, the sixth defector to cross from the Conservatives or Labour in recent months.

By Monday night, a still slightly stunned-looking Gyimah was on stage at “Glee club”, a rowdy and drunken annual fringe event where activists and MPs sing satirical songs packed with Lib Dem in-jokes. Two other new arrivals, Sarah Wollaston and Luciana Berger, were also amid the throng.

The one key policy change confirmed at the conference relates to Brexit, the party’s main election battleground. This is the notion that if Swinson’s party won an absolute majority in the Commons, admittedly an unlikely turn of events, she would immediately cancel Brexit, with no referendum.

Facebook Twitter Pinterest Luciana Berger takes a selfie with Chuka Umunna and Sam Gyimah, all recent recruits to the Liberal Democrats. Photograph: Peter Nicholls/Reuters

The plan was overwhelmingly supported by delegates as both a means of putting renewed distance between the Lib Dems and a Labour party increasingly warm on the idea of a so-called people’s vote, and of avoiding the paradox of fighting the election theoretically committing Swinson to finding a Brexit deal she would then disown.

However, there were some quibbles, more or less the only ones on show at Swinson’s honeymoon conference. Several delegates took to the podium to warn this was, in effect, a narrow, core-vote strategy, tickling the fantasies of urban-based ardent remainers, but doing nothing to expand the party’s reach.

Sir Norman Lamb, always something of a Brexit outlier among Lib Dem MPs, added another argument: such an absolutist position risked cementing division over Brexit. It was, he said, “playing with fire”.

But most senior party members seemed keen to endorse Swinson’s idea, or at the very least give her the benefit of the doubt. Sticking to the combustible theme, she warned a no-deal Brexit would be like “burning down the house”.

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Other election policies beyond the EU included an idea for a so-called wellbeing metric for future budgets, basing decisions on not just likely economic growth but also assessments of how they could affect people’s happiness and sense of purpose.

It is not a new idea – it was borrowed from New Zealand, and was also adopted by Labour two months ago – but was warmly received, and is seemingly aimed at giving a slightly more cuddly economic face to a party still associated with its role in the savage austerity cuts of the David Cameron-led coalition.

For the new recruits it was a great first conference. Berger and Wollaston spoke at length of the warm and positive reception they had been given from members. Chuka Umunna and Gymiah were spotted sitting next to each other, chatting away, on their train back to London.

Whether the honeymoon period of a party effectively reinvigorated and reformulated can last though will be a test for Swinson’s leadership. When an election is called and the squabble for seats unfolds between long-standing activists and newer members, it will take some resolve to steer what could be quite a fragile ship.