Something a bit weird going on?
Two things.
The paper the kid got handed by the police officer initially - http://www.wirah.com/en/event/17/photo/2851 - claims to relate to s5 of the Public Order Act 1986, but finishes with "If you are found guilty you may be liable for a fine or, under certain circumstances, a term of imprisonment."
What circumstances? The Crime & Disorder Act 1998 specifies only a fine for offences committed under s5. Imprisonment can be applied to s4 offences. See 31(5) here: http://www.statutelaw.gov.uk/content.aspx?ActiveTextDocId=1570330
Secondly, the police cannot issue a summons on the spot - they have to go via a Magistrates Court or the CPS. Yet all the reports say that the police "handed him a summons". The video on youtube has the police officer saying "Yeah, he's being summonsed"; 6:31, http://www.youtube.com/watch?v=d4lGYogQHIg
The Guardian quoted the CPS as saying "We did not advise on this specific case prior to the summons being issued – which the police can do without reference to us"; http://www.guardian.co.uk/uk/2008/may/20/1
So was a summons issued, and if so how? Or did the officer merely convert the Fixed Penalty Notice issued under s5 to a "report for summons" to allow them to request a summons to be issued, and if so how did both the police officer and the CPS spokesperson make the same error in describing what actually happened from a criminal justice perspective?