I'm glad to hear all is well at LHR... Would love to know the imbecile that set off the alarm though, keeping 235 pax happy locked onboard an aircraft, who have been delayed... and delayed... and delayed again, because we were grounded and couldn't push back was not the easiest of experiences! You guys that sit in the birds nests and the pointy ends deserve credit when it comes to dealing with difficult situations... When you're a member of 5 crew in that cabin with 235 angry faces glaring at you.... it's a bit difficult! Just hope the fool that caused such expense and trouble receives their just desserts!