I have a .co.uk site that ranks well (position no. 4 in Google and no. 1 in Bing). After 5 years, I've finally got round to registering the .com for the same site. As this doesn't need to be a .co.uk I'd effectively like this to be the main site from now on.
How will this impact my SEO? I can set a canonical URL to indicate the .com as the primary domain which would be the obvious choice if I'd registered the .com 4 years ago. I also know that doing nothing and keeping both domains pointing to the same site can have an adverse effect.
I have read many similar questions, but not able to find an exact answer. Any guidance appreciated. Thanks