Warmer outside on day to remember? (7)

I haven't cracked this one yet — but the brilliant team at Times for the Times have:

Cryptic with reference to ‘Guy Fawkes Night’ aka ‘Bonfire Night’ and the nursery rhyme: Remember, remember, the 5th of November, Gunpowder, treason and plot. I see no reason Why gunpowder treason Should ever be forgot. So far so good, but has anyone ever heard the rest if it? I’m sure I hadn’t before today! Guy Fawkes, Guy Fawkes, ’twas his intent To blow up the King and the Parliament Three score barrels of powder below Poor old England to overthrow By God’s providence he was catch’d With a dark lantern and burning match Holler boys, holler boys, let the bells ring Holler boys, holler boys God save the King!