Theresa May signalled yesterday that there would be a ballot on June 8 if Parliamentarians give consent today.

Brexit is set to dominate the short campaign, but other key issues are bound to come under the spotlight again, commentators have forecast.

Steven Cameron, pensions director at Aegon, said: “While Brexit related matters will clearly dominate June’s General Election, political party manifestos could reopen other contentious issues including pensions, savings, taxation and the changing nature of employment.

“This could include the future of the state pension triple lock, which had looked safe until 2020, the shelved increases in self-employed National Insurance and the unfortunate ‘will they, wont they’ debate on pensions tax relief reform.

“Whilst revisiting these policy areas may not be a vote-winner amongst pensioners, higher rate tax payers, or the self-employed, the opportunity exists for all parties to set out their stall on these key issues, creating much needed longer term stability.”

He said: “We may also see a new set of economic concerns rising in voters’ minds. For example, pensioners on fixed incomes are particularly affected by the ongoing uptick in inflation we’ve seen since the decision to leave the EU. Some older voters may start asking questions about each of the parties’ plans to ensure it doesn’t surge much beyond current levels.”

The shock announcement has already made waves in the markets.

The UK’s leading share index, the FTSE 100, had its worst day since the referendum, the pound hit two-and-a-half-month highs, and European stocks fell.

Nigel Green, founder and CEO of deVere Group, said: “Whilst these shifts can be perceived as knee-jerk reactions to the unexpected call for a general election in the UK, it can be reasonably assumed that it is also very likely to significantly contribute to the current wave of geopolitical headwinds, such as the French elections, that are helping to create volatility across the markets.”

Peter Hensman, real return team at Newton Investment Management, part of BNY Mellon IM, said: “Sterling has reacted positively to the prospect of a strong Conservative majority if the vote falls in line with latest opinion polls. For many, this will be seen as a second referendum on membership of the EU, the coming weeks will show whether this plays to strengthen the hand of the government as they begin, or will heighten uncertainty.

“The unexpected election further highlights the number of unknowns facing markets in the period ahead, with very little margin for error when markets stand at historically high valuations. Geopolitics, politics and monetary policy changes all have the scope to challenge becalmed financial conditions and warrant a cautious positioning.”

Stephen Findlay, CEO of BondMason, said: “In the short term, in the run up to the election there is likely to be a period of increased volatility in the markets and a potential pausing of investment decisions until the result is known.

“If, as predicted, the Conservative increase their majority in the commons, this will give them a stronger mandate to pursue Brexit negotiations and their broader aims and objectives, which may lead to great certainty and an appreciation of the UK currency over the medium term.

“Over a 12 month plus investment time horizon this move is probably a positive one for investors within the UK.”