I saw the best St. Patrick's day marketing by Guinness while I was in France: SymPatick Day. Oh man, I wanted to rip the poster down and take it home to show everyone it in all its witty phonetic glory.
One of the differences I think between England and Ireland, though, is that Ireland is viewed as a nation of alcoholics, specifically Guinness-drinkers. There isn't quite the same opportunity to exploit St. George's Day for a day of drinking by English breweries. But give a few years, the stereotype of the English as violent, louty binge-drinkers is setting in well.
I don't actually celebrate either, although I do indulge myself in a rut of pseudo-Irish cynical outrage every March 17th. I guess you could call that a form of celebration.
I'm completely of very recent Irish descent, but I grew up in England with parents who have English accents and although I spend a lot of time in the English-Irish community when I visit my family at least, I see myself as English. My whole irritation at St. Paddy's day celebrations comes from the fact that the day itself is hardly being celebrated in honour of Ireland.
Gaian British Guild
A haven for British Gaians, and those sympathetic to their peculiar ways!