Have a page for the pillar topic and one for the sub topic if you have the word count to justify it.

Otherwise sub topics can be H2s

if you have two separate pages I would avoid keyword cannibalization were possible. Keep your keywords on the page that target them.

However it may be necessary to talk in the context of pillar content. If you do mention the Pillar keyword, make it a text link to the pillar page. That way google will attribute the use of that word to the pillar page when ranking - and it will in fact strengthen the pillar page.

Does that make sense?

Thanks Miriam, This is very helpful and makes a lot of sense. What do you think of towns and villages, or boroughs of a large city. Do you think the close proximity is dangerous territory re: keyword permutations?

I take your point about unique content tailored to the people of the city - it makes a lot of sense. But what about locations that are closer to each other?

I know it's a tricky question but any insight would be most welcome.

Hi

Thanks for your response I'm interested in this too. I've been targeting cities with their own pages but I head recently that google are going to be clamping down on multiple keyword permutations. Do you think cities will be counted in this?

If the sub domain targets keywords not targeted in the rest of the website then rankings will slip.

I would 301 all webpages to relevant pages on your main site. Any important keywords should be monitored. You should crelated pages with content from the sub domain to maintain these keywords.

If traffic is non existent just 301 them.

No. The referring URL is a page on your site that has a broken link on it. These are damaging your rankings so so fix ASAP.  Go to all the referring pages and fix or remove the links with the URL in.

Yes this does not seem right. Did you check out the url the link is coming from. Is it in text with an anchor text. Or is it in a profile page?