The local authorities manage many of the public toilets and car parks within their districts or borough and provide information on their websites. A web link to those pages is therefore placed on each entry as a source of up-to-date information.
Those Public Toilets managed by local authorities:
King's Lynn to Burnham Overy Staithe Borough Council of King's Lynn & West Norfolk
Parish Councils, private businesses and conservation organisations who own or managed facilities often provide details on their relevant websites and links to these are also provided wherever possible.
Flush Toilet Finder is a free application developed by University of East Anglia student that displays the nearest toilets to you and has over 100,000 bathrooms in its database. See https://www.jrustonapps.com/apps/flush-toilet-finder