The claim is:

> Brexit: No-deal outcome could force shopping bills up by £800 a year, says union
>
> Tariffs imposed under WTO rules would increase the price of everyday goods such as butter, cheese and potatoes, analysis finds
>
> The cost of a family’s weekly shop could rocket by more than £800 a year if the UK leaves the EU without a deal, a major union has warned.
>
> Analysis for the GMB found that the bill for a typical supermarket basket of goods would increase by £15.61 a week – 17 per cent – if Britain was forced to fall back on World Trade Organisation rules, which require tariffs on many goods. 
>
> ...
>
> Under the WTO’s “most favoured nation” rules, the price of a 250g pack of butter would rise by 42p (up 28 per cent). Other increases would include 62p for a 460g block of cheddar(up 29 per cent), 43p for a pack of eight sausages (up 25 per cent), 32p for 2.5kg of potatoes (up 14 per cent) and £2.56 for a bottle of red wine (up 32 per cent), according to Acuity Analysis.

[Brexit: No-deal outcome could force shopping bills up by £800 a year, says union][1], Andrew Woodcock, The Independent, 8 June 2019

Things that make me feel sceptical about this claim:

 - I can't find a website for a research firm named "Acuity Analysis". There is a [Twitter feed here][2] which says "Providing unions with high-level strategic analyses to strengthen workplace democracy and enhance worker capacity for influencing decisions at the workplace."

 - I can't find the report itself on the GMB website or the Acuity Analysis twitter feed.

Things that make me think it might be true:

 - It makes sense that retail prices would rise under WTO (as opposed to EU) trade rules, because tariffs would be higher.

Are these figures plausible? Do they match other research done on this topic?


  [1]: https://www.independent.co.uk/news/uk/politics/brexit-shopping-bills-gmb-union-supermarket-price-rise-a8949896.html
  [2]: https://twitter.com/acuityanalyses?lang=en-gb