Ha, well, I see I've inadvertently started an SS vs PECI debate. So I guess I should pick a side, which for now....it's definitely gotta be Iron. I would consider SS in future but some of the suggestions made here don't seem to be available in the UK, plus after just 1 year there's no reason for me to be considering a paid replacement.
Now that we've settle that, 
@Jim Weber it's interesting that you mention that folks 'continue' setting the burners to high then complain etc but in fairness that is the standard cited practice, is it not? I'll certainly try a lower temp next time to see how that goes.
I think to be clear here folks I am not dismissing the suggestion that it's a cleaning issue. My abundance of caution is that my little boy enjoys grilling with dad and if there's a chance there's nasty bits getting in his food then obviously I want to be on the safe side. At the end of it I will have learned some valuable lessons. Weber asked for more photos, they are busy at the moment but I will take their guidance as well as on here.
Anyway now that we've opened up a few other discussions...I have more questions.
@Jim Weber again you said V side UP. Now I like this way BUT someone told me they were upside down and when i checked, even Weber said flat side up. But then I saw some were 'reversible' and left it to preference of how you like the sear lines. Is this a matter of opinion or fact, or was it just that 'upside down' was actually applicable to a different grate/model?
And also, if some of you are only deep cleaning very rarely, don't you get grease fires? I cook a lot but my cookbox, flavouriser bars and deflectors get filthy greasy. I don't use much in the way of glazes, I'm more of a dry rub guy in general. I cook a lot of chicken quarters. I've done 2 pretty deep cleans since April and both times a lot of crap came out.
Sam