David Bellamy talks about healing the world

Other guests at the week-long event, the largest of its kind in England and Wales, include Professor David Bellamy.

The botanist and broadcaster will be giving a live talk on Friday on ecology and the healing of the world.

The festival, which opened on Monday, has hosted 200 events covering topics ranging from the creation of virtual limbs to a cure for cancer.

The evening with Ken Dodd on Friday will be held at the North East Wales Institute.

As part of a study by the British Association for the Advancement of Science, audiences will be exploring issues such as whether or not men and women laugh at the same things.

And whether there is a north - south divide when it comes to humour.

One of the high points of the festival is expected to be an audience with psychic Uri Geller, who will be at the North East Wales Institute on Saturday, 23 March.

Geller became well known to television audiences in the 1970s for his claims to read minds, mend viewers' broken watches through mind-power alone and for bending spoons using the same technique.

Click here to join the Uri Geller challenge!

More than 15,000 visitors are expected to attend the festival and organisers have said hopes of meeting that target are high.

Festival spokesman Gareth Wheatley said: "We are delighted, we have had a number of people who have attended more than one event.

"There is a wider range of events this year and we have developed a wider audience geographically, people are booking tickets from further afield."

The festival was set up in 1998 and has been organised by Wrexham County Borough Council, Yale college, North East Wales Institute (Newi), the Welsh Development Agency and Education and Learning Wales.