Liberal Democrats have again called for a full investigation into how shamed Ian Oakley was able to wage his three year campaign of harassment, as his victims still wait for an official apology.

The national Conservative Party has remained silent since the former Tory hopeful in Watford pleaded guilty to 75 cases of harassment and criminal damage earlier this month.

The central party headquarters has said it will only comment once Oakley is sentenced, on September 16.

However, the party is again coming under pressure to find out why he was able to pursue his campaign for such a long time and to discover whether anyone else assisted his crusade.

Sal Brinton, the Lib Dem parliamentary candidate for Watford, said: “They must have a full inquiry so they can understand what happened, who was involved and what they are going to do to ensure it never happens again.

“And quite frankly they should be doing so. Any party should want to do an investigation so they can understand what happened.”

Ms Brinton, the principal target of Oakley, added: “We have had not one apology, not one of the victims in Watford has had an apology from Conservative Party.”

Lib Dem MP, Edward Davey, who grew up in Abbots Langley, wrote to Tory leader David Cameron a fortnight ago demanding a root and branch probe into the Watford Conservative Party.

In a second letter to Mr Cameron, sent on Tuesday, Mr Edward Davey said: “I deeply regret that a fortnight later you have failed to act in this matter or to apologise for the severe distress that this disgraceful campaign has caused.

“It is simply unacceptable for the Conservative Party to fail to address the very serious matters that have been raised as a result of this case.

“I trust that you will now act to rectify this shameful situation with a due sense of urgency.”