"... if a protected class is to continue to be recognised,
the class ought, logically, to include all classes in which
the relationship between the surety and the debtor is one in
which influence by the debtor over the surety and reliance
by the surety on the debtor are natural and probable
features of the relationship. In cases falling within this
protected class, security given by the surety would, in
certain circumstances, be unenforceable notwithstanding that
the creditor might have had no knowledge of and not been
responsible for the vitiating feature of the transaction.
Turnbull and Co v Duval (1902) AC 429; Chaplin and Co Ltd v
Brammall (1908) 1 KB 233; Avon Finance Co Ltd v Bridger
(1985) 2 All ER 281; Kings North Trust Ltd v Bell (1986) 1
WLR 119 and Barclays Bank v Kennedy (1989) 1 FLR 356 all, in
my opinion, provide support for this road.
In cases falling within this protected class, equity would
hold the security given by the surety to be unenforceable by
the creditor if: (i) the relationship between the debtor and
the surety and the consequent likelihood of influence and
reliance was known to the creditor; and (ii) the surety's
consent to the transaction was procured by undue influence
or material misrepresentation on the part of the debtor or
the surety lacked an adequate understanding of the nature
and effect of the transaction; and (iii) the creditor,
whether by leaving it to the debtor to deal with the surety
or otherwise, had failed to take reasonable steps to try and
ensure that the surety entered into the transaction with an
adequate understanding of the nature and effect of the
transaction and that the surety's consent to the transaction
was a true and informed one."