Thanks Matt - appreciate the reply.
Robots.txt are fine and I've check with other tools that the individual posts are not being blocked by robots.
WMT checks out fine too though the Crawl Rate is set to : Your site has been assigned special crawl rate settings. You will not be able to change the crawl rate.
Though the craw chart is indicating lots of crawling each day.
I do wonder about that crawl rate setting though. The site is using CloudFlare for speed optimisation and I believe that is a common occurrence when using CloudFlare.
I'll check out Screaming Frog though.....good idea.
Thanks again.