John Lloyd agrees with me a little more quickly than I had expected.

"Yes," he concurs, "at my age I should really be on my yacht."

The creator of (most recently) QI - a television series that is always on somewhere it would seem - as well as one of the main men behind The News Quiz, Not The Nine O'Clock News, and Spitting Image, producer of Blackadder and co-writer with Douglas Adams of The Meaning of Liff and some of The Hitch-Hiker's Guide to the Galaxy, could surely afford to cruise the Med if he so chose.

Instead of which, at the age of 63, he will be back at the Edinburgh Festival Fringe for the full run of dates with a show that is as yet not quite complete, and might be seen as his first tilt in the competitive stand-up bearpit. You can only assume that sailing has little attraction for him.

You may also judge that he enjoys the atmosphere of Edinburgh in August. Lloyd first returned to the Fringe in 2013 with a reminiscence show, The Liff of QI. It was his first appearance there since he and Adams had brought a student production to Brodie's Close in 1976. But he returned the following year with a stage version of radio's Museum of Curiosity and this year he is back with Emperor of the Prawns, a title that seems to tell us little except that there is always something slightly amusing about crustaceans.

Lloyd concedes that he could have trucked out the recollections that fuelled The Liff of QI at the Fringe ad infinitum, but explains that that part of the Indian Summer of his performing career has now been claimed by an entirely different audience altogether.

"That show kickstarted a whole new life for me, with a voice-over agent and on the circuit for after-dinner speaking, where I can soar off on whatever I fancy. I get to relax and have a four-course dinner in places like the Dorchester with CEOs and other people who are in their prime.

"I was a young TV producer when they were teenagers, so we saunter down memory lane together and have a great time doing it. I have seen more of the UK than ever before, and met people in the oil industry and the shipping industry, chartered accountants on the Isle of Man, and all of the ombudsmen. People who I would never otherwise have had the chance to meet, like Harrogate business club - 500 Yorkshire men and women who were a hoot!"

"So I decided that was not what to do on the Fringe. I don't want to always wallow in the past, so it was time to have a shot at something from a standing start."

Anyone who has watched Lloyd's clever TED talk about invisibility on the internet will nonetheless have a notion about the world of ideas that fascinates Lloyd.

His starting point there is that everything that matters is invisible, with the sole, and relatively small, exception of matter itself.

Emperor of the Prawns may contain some of the basket of ideas and fascinations that Lloyd casually lays out before me during our conversation. Like the business of plant intelligence, built on the evidence that barley is a genetically-weak plant that has survived because man has cultivated it assiduously to make beer, and that the discovery of the science of beer-making led to the development of farming itself and the civilisation of mankind. Hence Kenneth Clarke's much-admired and ground-breaking TV series owes its existence to a smart plant.

By a similar logic, Lloyd claims that dogs chose to be domesticated and in the company of humans because being a wolf was a fairly tough job, and meal times were more predictable in the village.

"So while some comedians like to talk about everyday things like family life and shopping, I want to try to make comedy from the big subjects. Like why water is one of the strangest materials we know, with about 40 ways in which it doesn't behave as physics says it should. I want to tease out these things, because the more you look at the world, the odder it becomes."

Which brings us back to the word "prawn", which, so says Lloyd, arrived in the English language out of the blue at around the year 1500, and for which no etymology has ever been traced. Its very singular oddity, he suggests, may be the simple reason why we find it funny.

John Lloyd's Emperor of the Prawns is at Assembly Checkpoint, Edinburgh at 4.30pm from August 6 to 30, except August 19.