The Dropkick Murphys have a reputation as the hardest hitting purveyors of Celtic Punk around, and on their return to London after an absence of a couple of years they more than live up to it.  After a fast-paced support set from the Bouncing Souls, the Murphys take things to a whole new level of frantic from the moment they explode onto the Roundhouse's stage, tearing through 'Hang 'Em High' and 'The Gang's All Here'.

Drummer Matt Kelly is particularly energetic, playing as though his bass drum is concealing a bomb and, as if in a percussive version of Speed, he's required to maintain a dangerous tempo in order to prevent it from going off.  The whole band's energy level is undeniably impressive, but something does get lost in the melee.  The Murphys play fast and hard on record, so when they crank things up even higher, their more melodic elements disappear amongst all the pace and distortion.

But then, maybe I'm one of the 'old bastards', of whom bassist Ken Casey says he can see many in the audience.  He makes this remark after describing how his grandmother attended one of their shows and complained that she couldn't understand anything the band was singing – and Ken's granny certainly had a valid point here.  So, in order to heed her feedback, and to appease the more mature members of the Roundhouse crowd, the Murphys incorporate a short acoustic set.

It's here that they really start to impress.  Singer Al Barr thanks the more devoted moshers for their patience during this quieter stretch, and comments that he feels there is a greater connection between band and audience when playing acoustic.  From where I was standing, that does seem to be the case.  Particularly impressive is the way that they gradually build up from acoustic to full-on.  'Warriors Code' is performed with neither drums nor bass, but the rhythm section and level of volume are slowly introduced as they work their way through a rousing 'Take 'Em Down'.  The banjo introduction to 'The State of Massachusetts' sounds like its part of the acoustic set, but the song as a whole is as storming as anything from the opening part of the show.

Having seen the Murphys playing acoustic – having heard the tin whistle and banjo, not the mention the lyrics, come across – it's easier to forgive them for being a bit heavy handed.  Dropping in some of their strongest tracks in towards the end of the set also helps: new single 'Going Out In Style' and the traditional 'The Irish Rover' are particular highlights.

But they save the best moment of all for the encore, which begins with the wryly charming 'Kiss Me, I'm Shitfaced'.  This is the essence of what Irish punk should be about – a jovial sing-along with plentiful energy and latent emotion.  An ladies only stage invasion helps to reinforce the connection between band and audience, and this is only increased when the men are invited up too as the Murphys blast through 'Skinhead on the MBTA' and a cover of AC/DC's 'Dirty Deeds Done Dirt Cheap'.  By now it might not be possible to see the band behind the fans who crowd the stage, but you know they're hitting it as hard as ever.