Sorry don't know - with discount codes we just normally try adding it at the checkout without completing the sale as a test .
These are the terms & conditions: "Enjoy £10 off any qualifying order of £50 or more with promo code BIGTHANKS
This offer ends on 25 January, 2018. One per customer. The offer applies to items dispatched from and sold by Amazon only. It does not apply to items sold by third-party sellers, including items Fulfilled by Amazon. More details below.
How to Claim:
Add any Qualifying Items with a combined value of £50 or more (the “Minimum Purchase”) to your Shopping Basket via the “Add to Basket” button. You cannot use the 1-Click ordering method when redeeming a promotional code.
When you’re done shopping, click the “Proceed to Checkout” button.
At checkout, enter the promotional code (BIGTHANKS) in the “Gift Cards and Promotional Codes” box. The Offer will then be applied to your order, reducing the cost of your total order value by £10.
Spend £50 or more in a single transaction (eligible items) dispatched from and sold by Amazon at the website www.amazon.co.uk (“Qualifying Items”) and £10 will be deducted from your total order value when you enter promotional code BIGTHANKS at checkout (the “Offer”). This Offer applies only to products dispatched from and sold by Amazon, excluding baby formula, digital products (Audible, Digital Documents, Digital Video Download, Digital Music Service, Digital EBook Purchase, Digital Software, Digital Video Games, Mobile Apps), pre-orders of physical Video Games products (games, consoles, accessories), gift cards (Gift Card, Gift Certificates, etc.) and delivery and handling charges. It cannot be redeemed on products sold by Amazon US or third party sellers on the Amazon Marketplace (including items Fulfilled by Amazon), at any of Amazon.co.uk’s Trusted Partner sites or at any other Amazon site, for example Amazon.com, Amazon.de, Amazon.es, Amazon.fr or Amazon.it. Each customer may claim a maximum of one Offer. This Offer cannot be used in conjunction with any other promotional codes or on any pre-existing orders. This Offer ends at 23:59 GMT on Thursday, 25 January, 2018.
Ensure that you have £50 or more worth of Qualifying Items dispatched from and sold by Amazon in your basket. Items which are dispatched from and sold directly by Amazon.co.uk can be identified by the message "Dispatched from and sold by Amazon" on the product detail page. Please note that items described as “Dispatched from and sold by Amazon US” are not sold and dispatched by Amazon.co.uk and are therefore not eligible for this Offer.
The Offer is subject to a Minimum Purchase requirement: (i) if you remove Qualifying Items from your Basket, so that the combined purchase value of the remaining Qualifying Items at checkout falls below the Minimum Purchase requirement, the Offer will cease to apply; (ii) if you cancel your order for a Qualifying Item (so that the combined purchase value of the remaining Qualifying Items falls below the Minimum Purchase requirement), the Offer will cease to apply; and (iii) if you return a Qualifying Item (so that the combined purchase value of the Qualifying Items you retain falls below the Minimum Purchase requirement), Amazon reserves the right to charge you (using the payment method you used for the original order and without further notice) for the discount you received as part of the Offer.
The Offer is subject to availability and may be withdrawn or amended without notice. The Offer has no cash alternative and may not be transferred or resold. If you place an order using the Offer and then return that order, the promotional code cannot be refunded or re-used."
Glad it worked for at least those that posted & hopefully a few more that spotted it (216 views) but didn't post.
We have 2 Amazon accounts so bought some more powerful & weather resistant walkie talkies for marshalling that have sat in our basket for a while now so £20 total discounted