McDermott has instructed Blackstone Chambers’ Monica Carss-Frisk as counsel.
Switalski, who is understood to be seeking more than £13m from the company, is being advised by Withers employment partner Elaine Aarons. Suzanne McKie of Devereux Chambers has been instructed as counsel.
The appeal is expected to be heard on 17 April.
In a statement, F&C said: “[We are] disappointed in the breakdown in trust between the company and Switalski which has resulted in an employment tribunal. Switalski made a number of claims against the company… the majority of which were not upheld. We vigorously refute all of the claims made against the company and an appeal is pending against the adverse findings made.
“In addition, we can confirm that no financial award has been made against F&C.”
Partnership expert Ronnie Fox of Fox Solicitors commented: “I am sure those who drafted the sex discrimination legislation never envisaged claims of this magnitude. I question whether employment tribunals are equipped to make the complex loss-of-earnings and injury-to-feelings calculations required to support awards of anything like this amount.”