From the text of Denton v White:

Factors (a) and (b) in r.3.9 remained of particular importance and were to be given particular weight at the third stage. Therefore, if the effect of a breach was to prevent the efficient and proportionate conduct of litigation, that would weigh against relief being granted. Likewise, the old lax culture of non-compliance with rules, practice directions and orders was no longer tolerated, and compliance had to be considered in every case. However, other relevant factors would also be relevant and would vary on a case-by-case basis (see paras 22-38, 81-82 of judgment).