Being as they are not owned by the parent fire service as such, and are government-owned, I would have thought they'd all the same. And they do get switched about a lot. IRUs are a post-9/11 response to the terrifying possibility of a terrorist attack involving chemical or nuclear agents. But that doesn't stop these impressive vehicles performing more mundane roles in - dare I say it - "peacetime".
Staffordshire Fire Service soon got rid of their chemical incident unit when the deputy prime minister kindly dropped off two of these gleaming beasts in Staffordshire. The IRUs at Newcastle and Burton are now on all of Staffordshire's PDAs involving chemicals. Well you might as well get your money's worth! There's no point in having many millions of pounds of tax-payers' money sitting around waiting for armageddon, when there's other work to be done!
Though I would't be surprised if brigades do tailor some equipment to meet their own specific requirements. After all these vehicles are huge, and are very easy to load and unload. Looking forward to reading the words of somebody that actually knows!
Added by Rob Johnson on 07 April 2014.