Chappell founded the sports-focused PR agency in 2002 after leaving his director-level position at Matthew Freud’s agency, which took an approximate 35 per cent stake in the new business.
Freud’s original investment in Pitch, which included other support such as back office resources, is understood to have been worth a five-figure sum.
It is understood Chappell acquired the last five per cent of Pitch from Freud in the first quarter of this year, thus taking full control of the agency.
The biggest chunk of Freud's stake changed hands last year, when Chappell bought 25 per cent of the agency for £500,000.
This generated a profit for Matthew Freud of £320,000, according to the 2012 accounts for Freud Holdings, published at Companies House this week.
Freud’s actual return on the investment is likely to have been much greater because it will include what he received for the remainder plus his share of its profits over the years.
It is understood the whole stake has cost Chappell in the region of a million pounds to acquire.
Last year, Pitch’s fee income grew by 20 per cent to £3.1m and employed 38 staff.
It has climbed to 66th place in PRWeek’s latest Top 150 Consultancies league table, while Freuds retained sixth place.
Freuds is one of the set of agencies PRWeek has identified as being "the breeding grounds" of the PR agency industry in its feature Six Degrees of Separation, which explores the relationships between established and new shops.