The UUP leader said it was "baffling" that this was being pinpointed as the reason for calling off the event, which was planned for the end of October.

Logistical reasons, including the fact that the UUP has just moved headquarters, were cited as the reason the party would not be ready for the conference.

Insiders, however, suggested it was also a factor that Tory leader David Cameron was being lined up as the potential guest speaker – and there was concern that the party may not be prepared when such a high profile guest was coming.

This meant not ready, in terms of running a smooth conference.

Speculation was that the real reason was: not ready to make an announcement on the outcome of merger discussions.

It was rumoured the UUP would like to have the headline act of the possible future prime minister at the conference and was prepared to delay the event to make that happen.

Additionally, some speculated the UUP-Conservative planning has hit difficulties.

But Sir Reg said it was all rubbish.

He said: "It is not unusual for political parties to cancel or reschedule their conferences."

Letters of invite to the conference had not even been sent out.

He continued: "However, in light of speculation I can assure you that we will indeed hold our conference irrespective of the state of our talks with the Conservative Party.

"Furthermore, may I add that the internal consultation (on the Tory issue] which is accompanying these talks will be ongoing."

As yet, he added, the behind-the-scenes debate has "not had a chance to become fully operational" as a joint working group has only recently been set up.

"Given that a joint statement from David Cameron and I was only released at the end of July during which time our Assembly was in recess, we have only had over one month to discuss the relevant issues," he noted.

"Do you honestly think that I would allow such important and significant decisions to be taken overnight? We will take as much time as is possible to discuss issues with the Conservatives.

"I find the amount of concern and speculation surrounding our conference postponement amusing and somewhat baffling. It will be rescheduled in the near future – the media will be kept informed of the date."

Alliance Youth chair Stephen Martin said: "The postponement of the Ulster Unionist Party Conference shows the terrible state their party is in.

"If they cannot even organise their own party conference, how can the public expect them to deliver in government? ]

"The news of this postponement tells everyone that their link-up with the Conservatives won't be happening at all."