Possible Clues:

• Speaking without preparation
• Winging it in promo, politician to throw away £1,000
• Big band playing around Long Island, performing without rehearsal
• Disregarding what's written
• Politician upset writer embraced by a BBC chief, improvising
• Sailor acquires Donegal Irish from search engine - making it up as he goes along
• Father returns to Long Island hostelry for gin cocktail, in a manner of speaking, off the top of his head
• Line I inserted in big band composition, improvising
• Improvising
• One big, bland, blundering improvisation