Indeed, it is axiomatic in the research sector that self-selecting survey samples are to be treated with a certain degree of scepticism.
Moreover, there is a legitimate question to be asked as to how necessary or valuable such a trophy is in an employment market where talented candidates heavily outnumber suitable job vacancies.
But whatever doubts one may have about the validity of this type of research, it is difficult to question the ambition underlined by Fishburn Hedges and Firefly's presence in the FT table. In short, they care deeply how potential employees perceive them and have made moves to demonstrate that.
PR companies devote a creditable amount of management time and money to making themselves attractive to staff. For those agencies that do not, there is a lesson in this.