Lively description found at A Journey Round My Skull:
When he wasn’t holding forth in a grog shop, he could be heard uttering unintelligibilities on radio or television. Edward R. Murrow cut out Behan from a broadcast citing “difficulties beyond our control”; on a television program where he appeared bombed with Jackie Gleason, the comedian said of him “Behan came across 100 proof—this wasn’t an act of God, it was an act of Guinness.” The Daily News quipped, “If the celebrated playwright wasn’t pickled, he gave the best imitation of rambling alcoholism you ever saw.” With tousled hair and rumpled clothes, Behan would attend performances of his own plays roaring drunk, taunting the actors, shouting epithets at them, and insulting the audience by screaming “Eejits!”
He reminds me of Dylan Thomas–perhaps the looks but also the behavior.