Mr Mayo has been on secondment to ICI since the beginning of the year and has been part of the small in-house team working on the implementation of the demerger proposals announced in July. He will join ICI in a 'senior financial capacity' next Monday, becoming finance director of ICI Bio on 1 January 1993.
That means Colin Short, currently finance director of the whole group, will stay with the bulk chemicals business, which will retain the ICI name.
The demerger will mean that the group's pharmaceuticals, agrochemicals and bioscience businesses will be floated off from the bulk chemicals businesses.
Mr Mayo, 36, joined Warburg's corporate finance division in 1984 from Arthur Andersen, the accountancy firm where he qualified as a chartered accountant in 1981. He was made a director of SG Warburg in 1990.
'I have been advising companies on what to do and how to do it for nine years. I'd be ducking something if I didn't put myself where my mouth is,' he said.