Thanks for your help everyone, you have answered my question very thoroughly!

I find it hard to recognize unnatural link patterns when the links to my site are so familiar.  It can be hard to see the wood for the trees!  How many links from one site is too many?  Does it depend on the size of the site?  Thanks for your advice on this.

Hello, to see all the links to a page have a look at Google Webmaster Tools (now called Search Console).  If you go to 'Links to my site' there is a list on the right called 'Your most linked content'. If you click on this it will give you a breakdown of the links to each page which Google are using as ranking factors.

Thanks!

Do you think having a link to your sitemap from your homepage is any use for SEO? I am getting mixed messages.

Generally people seem to be avoiding directories as they can be spammy and thin on content. I have had problems with getting huge numbers of no follow links from them. I would say avoid.

Now you come to mention it, I am having the same problem with my Squarespace site zenplugs.com.  The pages are indexing well but the images are mostly unindexed.  I would be very interested to hear any ideas!

Both pages are indexed now.  Well done!

Great pun in your question!