Sarah went shopping for Mr C, who wanted prawns, among other things! She grabbed a shopping list, instructions and £20 cash from Mr C's partner and dashed to Sainsbury's - as much as possible through the crowded Dalston market. A few substitutions were made at the supermarket including prawns, which were on offer and therefore sold out - but another brand was found.

Top tip: the checkouts are only taking card payments but are easiest to use if the total comes to over £20 and you have to take some things out... Thankfully Mr C had prioritised the list. If Sarah had remembered she was carrying various bits of change she could have then paid by card and been confident of returning exact change to Mr C. Instead she loaded up the shopping bags and put everything through the self checkout instead. Preparation is key! But so is memory.