rj87uk, this may help.
I had the same concerns, especially since when I changed hosts the number of pages indexed by Google was more than double my actual pages. I thought this had something to do with changing hosts and might create a duplicate problem resulting in drop in SERPs. I emailed to Google about this. Soon the number of pags was fixed and received the following reply (it includes answers to more issues I raised which I have ommitted since they do not concern this thread).
"Thank you for your note. We understand your concern that your site has
suffered or lost its visibility in Google search results because you
switched your hosting company. Changing your hosting company should not
impact your sites inclusion or ranking in the Google index. Please be
assured that your site is not currently banned or penalized by Google for
As you may know, our search results change regularly as we update our
index. Normal changes you observe may include, but are not limited to,
addition of new sites, changes in the ranking of existing sites, sites
falling out of the index or getting dropped for particular keywords, and
fluctuation between old and new webpage content.
We realize these changes can be confusing. However, these processes are
completely automated and not indicative of wrong-doing or penalization of
individual sites. We currently include over eight billion pages in our
index, and it is certainly our intent to represent the content of the
internet fairly and accurately.
While we cannot guarantee that any page will consistently appear in our
index or appear with a particular rank, we do offer guidelines for
maintaining a 'crawler-friendly' site. You can find these guidelines at
[google.com...] Following these
recommendations may increase the likelihood that your site will show up
consistently in the Google search results."