Hi Guys, thanks for the info.
DunedinDragon: In one simple phrase you have expertly described what an IR is and what it does. Someone at L6 should take that phrase
'The easiest way to think of IRs is they are "pre-cooked" cabinets. In other words when using a Helix cab block you specify what cabinet you want, what mic model you want to use with it, and where to position that mic relative to the speaker. An IR has all of this sort of information already baked into it, but it can't be modified. Therefore each variation of mic and mic position on a specific cabinet will be a different IR'
and post it on their page for people like me, great explanation.
Also thank you Zolko60, glad i'm on the right lines!
Cheers\m/