Mr Everard cannot have been dismissed for starting a website with the name pccc and posting porn on it.
Posting porn on the internet is not illegal in itself and BA does not own PCCC (I hope) so why did he get dismissed?
He apparently included BA-related keywords in the search parameters, such that searching for BA would lead to the porn site. Also, whilst PCCC may not be a BA entity, it clearly belongs to BA staff. Therefore his actions caused offence and injury to BA employees.
Also worth keeping in mind that there does not have to be any direct link between the employer and its employee in the specifics of any disrepute allegation. There is at least one decided case where an employer sacked workers for their behaviour completely independent of their work relationships. The case in question involved a number of Post Office workers who were caught on camera engaged in football hooliganism at the 2004 Euro Championships. They were sacked and their dismissals were upheld as fair.