A helpful case on Denton stage 1 in relation to unless orders and stage 3 in relation to the impact of a failure to act promptly. Jackson L.J. said,

“Part 1. Introduction
36. 1. This is an appeal by a defendant, whose defence has been struck out for non-compliance with court orders, against the refusal of relief from that sanction pursuant to Civil Procedure Rule 3.9. The principal issues in this appeal are:
i) whether, in assessing the seriousness of non-compliance with an “unless” order, the court should have regard to the original breach which gave rise to the “unless” order;
ii) the effect of delay in applying for relief.
[Stage 1] [Application to Unless orders]
37. In relation to this issue, the crucial passage in the authorities is paragraph 27 of Denton. [He cites from Denton]
37. In my view the reference in the first sentence of that paragraph to “unrelated failures” is a reference to earlier breaches of rules or orders which the applicant has committed during the course of the litigation. At stage 1 it is not legitimate to say “this breach is trivial but, set against X’s history of failures and delays, this breach is the last straw. It becomes a serious matter.” At stage 1 the court must ignore X’s historic breaches and assess the breach in respect of which X is seeking relief.
38. An “unless” order, however, does not stand on its own. The court usually only makes an unless order against a party which is already in breach. The unless order gives that party additional time for compliance with the original obligation and specifies an automatic sanction in default of compliance. It is not possible to look at an unless order in isolation. A party who fails to comply with an unless order is normally in breach of an original order or rule as well as the unless order.
39. In order to assess the seriousness and significance of a breach of an unless order, it is necessary also to look at the underlying breach. The court must look at what X failed to do in the first place, when assessing X’s failure to take advantage of the second chance which he was given.
40. In my view the phrase “the very breach” in paragraph 27 of Denton, when applied to an unless order, means this: the failure to carry out the obligation which was (a) imposed by the original order or rule and (b) extended by the unless order.
41. The very fact that X has failed to comply with an unless order (as opposed to an ‘ordinary’ order) is undoubtedly a pointer towards seriousness and significance. This is for two reasons. First, X is in breach of two successive obligations to do the same thing. Secondly, the court has underlined the importance of doing that thing by specifying an automatic sanction in default (in this case the Draconian sanction of strike out).
42. On the other hand, as Mr Weston rightly says, not every breach of an unless order is serious or significant. In Utilise the claimant was just 45 minutes late in complying with an unless order. He filed his budget by 4.45 p.m., rather than 4 p.m. when it was due. The Court of Appeal held that a delay of only 45 minutes in compliance was “trivial”. The court also noted that, contrary to the district judge’s view, there was no underlying breach of the rules onto which the unless order was attached.
43. After this review of the authorities, let me return to the present case. BB had three months to comply with the 1st November order. They did not do so. They filed their PTC 18 days late by reference to that order. BB received the unless order on 13th February (not 17th February as Judge Harris was led to believe). They had six days in which to comply with the unless order. They failed to do so. The document which they filed on 18th February was not a PTC. Furthermore its contents bore no sensible relationship to the current litigation. It proposed that all sorts of steps should be taken long after the fixed trial date.

[Stage 3] [All the circumstances]
52. In relation to stage 3 of the inquiry, the correct approach is set out in paragraphs 31 to 38 of Denton. The court must consider all the circumstances of the case, but must attach particular weight to the following factors:
“the need –
(a) for litigation to be conducted efficiently and at proportionate cost; and
(b) to enforce compliance with rules, practice directions and orders.”
53. The majority in Denton rejected my heretical view that those two factors require specific consideration, without carrying greater weight than other relevant factors. I must and do loyally accept the decision of the majority.
54. The court stated in paragraph 36 of Denton that the promptness of the application is a relevant circumstance to be considered. The importance of applying promptly for relief is stressed in the earlier authorities…
55. Let me now turn to the present case. It the defendant had made an immediate application for relief at the same time as filing its PTC, or very soon after, I would have been strongly inclined to grant relief from the sanction of striking out. To debar a party from defending a £200,000 claim because it was somewhat late in filing a PTC is not in my view required by rule 3.9, even as interpreted by the majority in Denton.
56. As at 21st February the late filing of the listing questionnaire had not had any adverse impact on the smooth conduct of the action. The moderately late filing of a PTC is not like the late service of evidence or the late disclosure of documents. It does not disrupt the work schedule of any other party to the action. The PTC is needed for administrative reasons, except in those cases where the court dispenses with that procedural step. The late provision of the PTC in this case did not have any adverse effect on the administrative processes of the Oxford County Court.
57. If, therefore, the defendant had promptly applied for relief from the sanction, in my view this is a case where one of two things would have happened. The claimant may (and should) have consented to the application. Alternatively, the court would have acceded to the application when applying stage 3 of the Denton test.

61. In my view the defendant’s lack of promptness in applying for relief is the critical factor. When that delay is added to all the other factors, it can be seen that the defendant’s default has substantially disrupted the progress of the action. Bearing in mind factors (a) and (b) in rule 3.9 (which under Denton must be given particular weight) there is really only one answer to the question which arises at stage 3. The court must refuse the application for relief.”

Edited for ease of reading.