Tony,
I do hope that you are not a New Business Director or in fact looking to put your finger in a pie or two...
Typically the big clients' business is handled by the AAR or the Haystack Group (these are Pitch specialists). Marketing Directors will appoint a pitch specialist to their piece of business, and then that specialist will take into consideration the nature of the business and the best agencies for the job and then set up chemistry meetings and a pitch process, in which shortlisted agencies will pitch for the business through strategic ideas and creative suggestions.
Alternatively, agencies who do not want to pay out for a 'middle man' will appoint an agency without a pitch, typically a marketing director who is familiar with an agency's work or way of thinking.
However, this is not to say that agencies can't just contact clients who require a new agency or look bored with their current communications. So, who is your daddy and what does he do? In other words - are you an agency looking for clients? If so, get searching for brands that reflect your very nature.
Good Luck