While checking the company's website for vacancies, I saw two potentially suitable roles but had been listed for some time (11 months) at the headquarters in the UK and so emailed the HR department - as per the application instructions - enquiring whether the roles were still available, and potentially to avoid wasting anyone's time. This was in December 2017 and going by the complete lack of response can only assume I was not successful in my pre-application query...
If these reviews are to be believed, it seems possible that Sophos as a company has a running history of ignoring applicants/staff/customers. It has been a most enlightening experience regarding the company, and convinced me that I do not want to work for them.