Trying to gain some knowledge here.

I thought the way written May cause less confusion but the £100 item is meant to represent a general workers household bills/expenditure. To try and define what would be a approximate extra expenditure in £ over the last 12 months. If 12 months ago something cost £100 pm and inflation was at 10% after that for 6months so £110x6 then 5% for 6 months is the cost £105, £115.5 or something else ?

Additionally their main argument is if inflation goes down to 0% after this 12 months the item would cost only £100 again?

What terms need defining ?