David Dimbleby could make an unexpected comeback as BBC election night host as the corporation begins to secretly prepare for an emergency election in case Theresa May’s government collapses.

News at Ten host Huw Edwards was due to take over duties as the main presenter of the BBC’s coverage following the 2015 general election.

But Dimbleby, who has hosted every general election night for the BBC since 1979, instead unexpectedly returned for both the 2016 EU referendum and the 2017 snap general election.

These were thought to be his final appearances but BBC sources say the current arrangement, which is subject to change and final approval from BBC executives, would mean any election held in 2019 would once again be presented by Dimbleby.

Edwards is still expected to host the following day’s TV coverage, which can attract higher viewing figures but does not come with the prestige of being able to announce the exit poll result and call an election. As things stand Edwards would then take over the main slot from Dimbleby for any election night from 2020 onwards.

A BBC spokesperson declined to comment on “speculation” about presenters, including the extent of of internal preparations for a snap vote. Dimbleby’s agent did not return multiple requests for comment.

Executives are said to be keen to stop preparations for an election from leaking to the media, to avoid the impression that the BBC is seen to be pre-empting ongoing political events. However, they are considering all options to ensure they are ready to activate their plans and deploy staff at short notice.

As a result the corporation has inquired as to the availability of Elstree Studios in Hertfordshire, where the BBC often hosts its coverage of major political events. If the studio is not available then they could be forced to host the live programme from the corporation’s New Broadcasting House headquarters, although this could require the BBC to use a scaled-down set.

Issues of studio availability are complicated by the lack of a clarity on when a general election – or second EU referendum, which would require a similar level of preparation – might be held.

Other concerns include potentially commissioning new graphics and ensuring exit poll teams are prepared and whether the BBC would be required to host debates between party leaders – with the corporation already potentially involved in hosting a Brexit debate next month featuring Theresa May and Jeremy Corbyn.

Dimbleby, 80, is due to step down as host of Question Time next month with Fiona Bruce offered the chance to replace him.

The Dimbleby family have been intrinsically associated with televised coverage of British general elections since 1955, when Richard Dimbleby began hosting the BBC’s programming.

David Dimbleby, 80, first appeared on a BBC election night broadcast as a junior reporter in 1964 alongside his father.

Richard died the following year, creating a 15-year interregnum during which the public had to cope without a Dimbleby hosting the broadcast before David was promoted to the top job.

David’s brother, Jonathan, the current host of Radio 4’s Any Questions, anchored ITV’s election night coverage between 1997 and 2005, meaning that for a decade terrestrial viewers had no choice but to learn the election results from a Dimbleby.