Originally Posted by
GUWonder
You could use a refundable/changeable ticket to get airside at OSL and then make your way back to look around the baggage claim area that way.
I'm not sure how that would have worked; I don't know that the departures area is physically connected to the arrivals area. Regardless, it's not necessary, as OP already discovered.

To anyone in a similar situation in the future, the baggage service people have a procedure for this: they call a security agent over with a wand, to check for weapons, and then they'll have one of their people escort you through into the baggage area.
Originally Posted by
nacho
What did your luggage claim tag say? LHR or OSL?
If they said LHR, then they are definitely going to baggage claims at LHR.
That's simply not true. Bags can be re-routed en route. I was on a similar itinerary, XXX-iAD-LHR-YYY, and I originally had a 15 hour layover at LHR, meaning my bags were only tagged to LHR by UA policy. Upon arrival at IAD, I was able to make a change to a later IAD-LHR flight, making my new layover at LHR 11 hours. My bags were re-tagged to YYY (without my knowledge); when I went to pick them up at LHR, I found out they'd been transferred on to my final destination, even though I never got an updated luggage tag. When I got to YYY, my bag arrived along with me.