Many accountancy firms fail to appear in one of the most effective sources of new leads when prospects are searching.... the first page of Google.
While many have put in the effort and generate a regular flow of suitable leads, many other practices either fail to make it a priority or are in denial about its benefits (which of course becomes a self-fulling prophecy).
Not sure where your practice appears?
Simply open up a browser and type in the sort of search a potential client would make (NB - not your firm's name! Also, best done from a private browser window to stop your results being skewed by your browsing history).