There is no evidence that ties Prince William to the company Serco.
Serco was founded in 1929 as RCA Services Limited, a United Kingdom division. RCA Services Limited was bought by its local management and changed its name to Serco in 1987 and has been a London Stock Exchange-listed company since 1988.
The company's website has updated the existing ownership profile, which is heavily weighted in favour of institutional shareholders which is 95%. Private shareholders holding in their name on the share register represent only around 1% of the Company ownership, with private brokers and wealth managers representing a further 4%. Nowhere there is mention of Prince Williams being a shareholder of the company.