Possible Clues:

• Rapture
• Chopper's up -- film director coming into London for larks
• Joy, it's time to get into breathing out, having dropped an aitch!
• The collective noun for larks
• High praise
• Getting high with blow, taking time — but not heroin
• Group of larks
• Extreme happiness
• Rapture at being accepted by Texan oil organisation
• Pound provides several examples of such rejoicing