First, I must admit, I don't know. This goes beyond my experience, but if your client uses an accountancy firm, perhaps they can give you an answer.
What follows is opinion only.
The first thing to say is that restoration does not happen until the Registrar is satisfied that all outstanding matters leading to the striking-off have been rectified. Thus, as the effect of a restoration is that the company is deemed to have continued in existence (emphasis supplied) as if it had not been dissolved or struck off the register (ss 1028(1) & 1032(1) Companies Act 2006), it seems to me that, all other things being equal, the brief hiatus in its legal existence will not materially affect the accounts, and to mention the striking-off and restoration would be irrelevant. Furthermore, if the company is a "small" company (ss 381-384) then it only has to file its balance sheet under the small companies regime, and the notes to those accounts will relate to that "snapshot in time" only, and not to the preceding trading period. In other words, the striking-off will not need to be referred to.
A small company does not have to submit a Directors' Report (s444(1)(b)), and even if it does so, it does not have to include a business review (s415A), where such an event would likely be mentioned.
So I believe no mention need be made of the striking-off in the financial statements.
Even if the company does not qualify as a small company, I believe the fact that the company is deemed to have continued in existence strongly argues that the accounts are unaffected, and the business review in the Directors'' Report should not have to mention it because the striking-off and subsequent restoration would have had little impact on their duty to promote the company's success.
