For those that have multiple American Express cards or even just the one card with a supplementary card holder, check and see if you have the Jessops spend £150 and get £50 back as statement credit.
If both cards have it available then save them to the cards and ask to split the cost of the GoPro Hero 5 across the 2 cards and you will receive £100 back. They are definitely able to do it in my local jessops.
£249 is a great price for the brand new Hero 5. I know this offer won't suit everybody but the jessops offer is in both my gold Amex and British airways Amex as well as the supplementary cards attached.
The same principle could be applied to any items over £300. Or in multiple of £150 if a) you have enough Amex cards and b) the sales agent will split the bill across them all.