The missing ballot papers did not alter the election results

The company said "human error" was to blame after 957 Test Valley Borough Council postal votes were sent to a wrong address in Andover.

As a result the returning officer did not receive the votes until 14 May.

The ballot papers have now been counted and they do not affect the result of the election on 3 May.

In a statement Royal Mail said: "We have apologised to the council for this, which, our investigations show, was due to human error - the batch of postal votes became mixed up with a larger mailing and was sent to the wrong address.

"Lessons have been learned from this experience and we have strengthened the checking process to ensure this does not happen again in the future."

Tory gain

The council's returning officer successfully applied to the County Court in Southampton to open and count the missing council and parish council votes after they were tracked down.

This was done on Saturday at the council's Beech Hurst offices in Andover.

In a statement, Test Valley Borough Council said Saturday's count would "allow the candidates of these elections to make an informed decision about whether to apply for an Election Petition concerning their individual election results".

The election saw the Conservatives increase their representation by two councillors (33) at the expense of the Liberal Democrats (15).