Uncounted postal votes may have changed the result of the local election in Brighton and Hove, a Freedom of Information request has revealed.

Four candidates, including the former deputy council leader Hannah Allbrooke, may have been elected to the city council in May if more than 1,400 postal ballots had arrived on time.

Some 1,423 postal vote packs were delivered late to the council, arriving at 8am on May 5 - some ten hours after the polls had closed in the local election earlier this year.

The number of late-delivered postal vote packs could have shifted the result of four wards decided by narrow margins. And it is feared some of the late postal votes were held up in the postal system longer than expected.

A Freedom of Information request, filed by Ms Allbrooke, has revealed a breakdown by ward of the postal votes that arrived too late to be counted.

Based on the data, Ms Allbrooke and fellow former Green councillor Leo Littman could have been elected depending on the results of the uncounted ballots.

Ms Allbrooke, who lost her seat in Brunswick and Adelaide by six votes, could have maintained her place on the city council had 63 uncounted postal ballots for the ward been taken into consideration. The votes chosen on the postal ballots not counted have not been revealed.

Mr Littman also lost his place on the city council by 32 votes in Preston Park, where there were 98 postal votes that arrived late.

In Regency ward, where Green candidate Ricky Perrin lost by just one vote, 47 postal ballots arrived late and were not counted.

However, even if all three Green councillors had been elected, Labour would have still comfortably secured majority control of the council for the first time in 20 years. The results would have taken the Green Party to ten councillors, with Labour on the slightly reduced number of 35 - well above the 28 needed for a majority.

Labour candidate Lundy Mackenzie, who lost by only 100 votes in Westdene and Hove Park, may have also missed out on being elected as a councillor by the postal delays.

Some 118 postal vote packs for the ward arrived too late to be counted - the largest number of any ward in the city.

Labour’s Peter Devonport may have also beaten his fellow candidate Alison Thomson for a place on the city council, after missing out on a seat in the ward of Regency by 13 votes.

The revelation comes around a month after Green group leader Steve Davis questioned the legitimacy of the election result due to the number of uncounted votes.

The council said that it cannot be confirmed if the packs that arrived late contain ballot papers or valid postal voting statements because they “cannot be opened”. As a result, it is not possible to say conclusively whether a different result would have occurred if those votes were counted.

In a response to questions over postal votes, a spokesman for Brighton and Hove City Council said that by law postal voting packs received after polls close cannot be opened or included in the count.

He said: “The returning officer only included in the verification and count ballot papers cast by the close of poll.

“All postal voting packs that were received by the close of poll were opened and their personal identifiers were checked - as required by law.

“The count of ballot papers was observed by large numbers of candidates, election agents, count agents, guests and the media on Friday, May 5.

“All provisional results were agreed by candidates and/or election agents prior to their declaration. Candidates and election agents were given the opportunity to ask for recounts and the deputy returning officer took a proactive approach to calling a re-count for Regency ward due to the closeness of the result.

“No results were declared without the agreement of candidates and/or election agents.”

A spokeswoman for the Electoral Commission said: “Legally, once a returning officer has declared a result at the count, it is final and cannot be amended, unless they make an error in their oral announcement and correct it immediately.

“For an election result to be challenged or changed, an election petition must be brought through the courts.

“A petition at a local government election must normally be presented within 21 calendar days after the date on which the election was held.”

Brighton and Hove City Council and Hannah Allbrooke were approached for comment.