The British National Party (BNP) is demanding a full and frank criminal investigation after thousands of General Election leaflets allegedly went undelivered by Royal Mail staff.

The party claims that up to 3,000 leaflets may have been deliberately misplaced by staff at Watford’s Ascot Road sorting office – meaning that they went undelivered to homes in the Bedmond area.

As a result, activists are suggesting, Parliamentary candidate Deirdre Gates was robbed of vital votes in her unsuccessful campaign for the South West Hertfordshire seat.

Party activist Simon Deacon claimed the party’s fifth place finish, behind the United Kingdom Independence Party, could have been improved if the leaflets had reached their intended destination.

He said: “We don’t know what difference these leaflets could have made, whether they would have improved our result or not, but we only just behind UKIP – who we wanted to beat.

“The worse thing is that we will never know because somebody at the Post Office decided that some people should not see these leaflets.

“We are upset because they cost a lot of money to produce and that people haven’t seen them.

“I think it should be up to the people Bovingdon what leaflets they choose to read.”

Royal Mail confirmed yesterday that an investigation into the matter was ongoing but chose not to comment directly on the party’s claims.

Hertfordshire Constabulary, meanwhile, confirmed this afternoon that it too was investigating the party’s claims.

A spokesman said: “We’ve been made aware of a complaint and are working with the Post Office whether any criminal activities have taken place.”

Deirdre Gates, who represents the South Oxhey ward at Hertfordshire County Council, has been unavailable for comment.