Research - The key to inspiration?

Research. It's a fundamental aspect of writing. Making sure you know what you're writing about so that your audience doesn't catch you out.

The thing is, when is research classed as procrastination? I think this is one of the main weaknesses I have from actually getting down to writing. 

For instance, I recently watched the BBC adaption of Wolfhall. It's set in Tudor Britain, which is a time period which interests me greatly. I had the inspiration whilst watching the show, of creating an antagonist in my upcoming novel which is machiavellian, only out to get what they want, trying to continually rise in social status. 

So, after my 'light bulb moment', I sat at the computer, and looked up some Tudor related pages on Wikipedia (the fountain of all wisdom and knowledge in the 21st century!)

After reading all about Henry VIII and his six wives, I became interested in the age he was when he married each one and when his children were born. This lead to a chronological timeline of the life of Henry VIII, which is now sitting in one of my (many) writers notebooks gathering dust, for I will never use this... Unless I decide to write a story about Henry VIII, which, let's face it, has been done numerous times, very well, so unless I get a burning and fantastic desire to write a story about Henry and his wives, the 'research' stops there.

This is when research turns into procrastination, or useless information overload. I don't have a clue how this information helps me progress my novel in any way, I didn't even research general machiavellian character traits, or something similarly useful in my idea for my antagonist. 

The best part of a whole day wasted on needless 'research' which actually has no bearing on the plot of my story at all, and it happens, literally all the time. I really need to focus more on the task in hand instead of literally 'going off on a tangent'!

Let me know, do you sometimes find it difficult to contain your research to what is necessary? Do you have any tips on how I can contain my wandering brain to make my ideas and research useful and inherent to the plot?