Haynes has already published Man and Baby manuals

Haynes is well-known for producing manuals which explain to drivers how particular makes and models of cars work.

The manuals use diagrams and step-by-step instructions to tell amateur mechanics how to fix their cars.

The Sex book will follow a similar style, say the publishers.

Plans for the latest edition follow Haynes' two highly successful Man and Baby books.

Company chairman John Haynes said the book, a down-to-earth guide to sex, would be released in time for Christmas.

He said: "There is no slant to our manuals - that is their success.

"They just tell people what they need to know in a straightforward way with pictures and diagrams."

The announcement of a new book in the series came on the same day Haynes announced it had sold seven million manuals this year.

The Somerset firm saw annual pre-tax profits more than treble to a record �7.1 million in the year to 31 May.