Travel within my country of residence

The plans you mention above are fine. 

You’re not restricted to one train; you can take as many as you need. You’re not restricted to travelling to/ from St Pancras - any departure port is fine, and you can take your UK travel days at any time during the validity of your pass.

But for completeness, you can only use them in connection with an international journey. You can’t travel from London to Aberdeen then not fly to Oslo.

Thank you ​@rvdborgt for such a clear and concise response … I can now get down to planning my trips and what ticket I will need.  :)

Hi ​@ralderton and thank you for your extra piece of information re must travel abroad.  Does the ongoing travel have to be the same day?  If not how long a delay can there be?  And I have to ask … how will they know, do I have to produce an onward travel ticket on demand?

​@firlandsfarm - the answer is . . . they won’t know.  There is no way for the ticket inspector on the train or at the station to know whether you plan on leaving the country, unless of course you care getting a train to somewhere that that you cannot in any way leave the country from, and there can’t be too many of those places.

I don’t think it’s specified anywhere in the conditions. Next day should be fine though  

The inspector is, I think, entitled to ask to see your proof of international travel, though they’ve never asked for mine. 

Hi ​@ralderton I suspect it’s one of those ‘silly’ rules that the rule setters think sounds good but has not been thought through fully and is not policeable.  How would it be policed if the ticket/user originates in a Schengen country travelling to another Schengen country?!

BTW would I be correct to think ‘origin’ is set by the ticket holder’s passport and not where they are on purchase nor where they actually live day to day.  So for example someone who lives in a different country than the one that issued their passport can buy a Pass and use it to travel around the country they live in being different from their passport?  

Your country of residence is what's important. That's normally where you are registered. There are some nuances, see section 5.2 in the Pass Conditions of Use.

The reason the rule exists, is to protect revenue for the train operator. If a resident could use an Interrail pass freely, even commute, in their own country, there are plenty of countries where people would do that instead of buying more expensive tickets. Whereas in a foreign country, the opportunity and desire to do that is reduced. 

The rail pass simply couldn’t exist in its current form & price if the rule wasn’t in place. Operators wouldn’t sign up

It does rely on an element of self policing. There are some countries where ticket inspectors rarely check, and others where they definitely will!

Your country of residence is what you tell Interrail, and it’s usually pretty clear. 

Thanks ​@ralderton I realised why they have the rule … I was just questioning how it’s determined.  In the past I have been asked to produce my passport sometimes on mainland Europe (strange when I clearly sound ‘British’!).  I see 5.2 effectively says it’s your passport country unless you can prove otherwise.  Makes sense.

That’s also an ID check. Particularly common in Switzerland, but technically any inspector can ask you for the ID you used when you activated the pass. I’ve only been asked once in the UK.