Buchanan Communications had the most clients with 122.5 (a joint advisory is recorded as 0.5 of a client).
Brunswick had 83 clients, while Citigate Dewe Rogerson had 70 on its books.
When client numbers for the three months to 6 October 2004 are compared with those for the same period last year, eighth-ranked Lansons Communications is the only agency not to have increased its client tally. It had 48 clients this time around, a fall of nearly 13 per cent from 55 in October 2004.
Lansons joint MD Ian Williams said the agency had been hit by a contraction in the investment trust market, but he added that Lansons' fee income was up 13 per cent from January.
Hemscott's two other tables, which rank City communications agencies by their clients' profit and market capitalisation, paint a different picture.
FD, whose clients' market value increased by 11 per cent, was third by client market cap. Brunswick and The Maitland Consultancy were first and second respectively, both in terms of client market capitalisation and total client profit.
Finsbury, whose clients' profits declined from £13bn to £6.8bn, was third in the clients' profit table.
'While the data show that nearly every agency has increased its number of clients in the past year, those with the most clients were often working for smaller firms and therefore did not make it into the client profit and market cap tables,' said Hemscott chief executive Ros Wilton.
'Agencies with clients in industry sectors such as oil production have done particularly well,' she added.