defendants knew the identity of the Hart defendants prior to late
2015. Thus, prior to that date, they did not have actual knowledge
of the facts necessary to make a claim for contribution and
indemnity against the Hart defendants. Accordingly, they have
rebutted the presumption of actual knowledge in accordance with
s. 5(2) of the Act, and their claim for contribution and indemnity
is not barred by ss. 5(1)(a) and 4 of the Act.
Requirement of Due Diligence
 As noted earlier, s. 5(1)(b) provides that a claim will be
“discovered” on the day on which a “reasonable person with the
abilities and in the circumstances of the person with the claim
first ought to have known of the matters referred to in clause
[5(1)(a)]”. This provision applies generally and is not limited to
claims for contribution and indemnity.
 In Fennell, van Rensburg J.A. noted that a plaintiff is
“required to act with due diligence in determining if he or she has
a claim, and a limitation period is not tolled while a plaintiff sits
idle and takes no steps to investigate the matters referred in sec-
tion 5(1)(a)”. van Rensburg J.A. made the following comments
with respect to the role of due diligence in the application of
s. 5(1)(b) [at para. 24]:
Due diligence is part of the evaluation of section 5(1)(b). In deciding when a
person in the plaintiff’s circumstances and with his abilities ought reasonably
to have discovered the elements of the claim, it is relevant to consider what
reasonable steps the Plaintiff ought to have taken. Again, whether a party
acts with due diligence is a relevant consideration, but it is not a separate
basis for determining whether a limitation period has expired.
 The Court of Appeal elaborated on these observations in
Galota v. Festival Hall Developments Ltd.9 In Galota, the plaintiff
broke her arm when she fell off an elevated dance floor at
a nightclub in downtown Toronto. She sued the tenant and operator of the nightclub. At the time of the commencement of the
claim, she was unaware of the possibility of a claim against Festival Hall, the landlord and owner of the building, and took no
steps to investigate the possibility of any such claim.
 She subsequently learned of the possibility of a claim
against the landlord and commenced an action against Festival
Hall. Festival Hall moved to strike out the action against it on the
basis that the plaintiff had not brought the claim within two
years of the date upon which it ought to have been discovered.
Festival Hall argued that because the plaintiff had taken no steps
9 (2016), 133 O.R. (3d) 35,  O.J. No. 3906, 2016 ONCA 585 (“Galota”).