The simple answer is that Thunder Screen Reader (which is free) does not like tables, pictures and some layout tags and gets confused or stops reading, so I have set up a site with no formatting, pictures, graphics or tables of information and also has some spelling changes because of the way it pronounces some words. Other readers may not have the "problems" that Thunder has but they cost, quite literally, hundreds of pounds to buy. The Visually Impaired site resides in the VM webspace so that the adverts (now gone) don't confuse the issue even more.
Update 27 Jan 2008. There were 2 sites, but, since I taught myself about Cascading Style Sheets (CSS) there is only one site spread acrodss the 2 servers.
Using CSS for formatting the pages made them accessible to screen readers without the confusions caused by the way they were formatted before and negated the need for a 'plain' site. All the content is now in one place, with some 'extra' pages where required.
Update: 23 Nov 2008. The whole site has now been moved to the Free Web Hosting Area server.