No, that looks like it is Free Delivery. Most orders over £20 seem to be eligible for FD. Just don't check the box which offers you 'one-day delivery with Amazon Prime'.
I signed up for prime it more than pays for itself especially on small items that can carry disproportionate delivery charges but I will not renew it this time though as I will be cutting back drastically on my shopping.
Like you, I only shop on Amazon occasionally, and I don't mind waiting a few days for my delivery. It is a nuisance having to spend £20, but I could cope with that. However, now a lot of items are cheaper for Prime members only, and I have moved to EBay as my first shopping choice.