I have Britrail passes for June, for trips to Norwich, Lancaster and York. I am advised that reservations are not needed for these trips; in fact, Britrail says they cannot make reservations for any trip scheduled under 3 hours.

Any comment or suggestions as to the probability of getting seats for these trips on a walk-up basis? (AM departure London-Norwich mid-June, return PM; AM departure to Lancaster; PM return from York)

It will depend partly on the day of the week. For long journeys, trains are generally busy around weekends, particularly with people going away on Friday evening or Saturday morning, and returning on Sunday afternoon and evening. If you want to return from York to London on a Sunday evening, the train is likely to be packed. If you want to reserve a seat, it's easiest to do so once you're in the UK. I've never heard of any limit on the length of a journey for reservations - you can certainly reserve a seat for a journey of less than three hours. Seats on the London-Norwich journey, for example, can be reserved for £1 each.

Been on a zillion British trains - 1st class is rarely, never in my experience full, often half full. Standard (2nd) class is often quite full or more and more full. British trains have seen Europe's largest increase of any country in train use and thus 2nd class is more crowded as the public responds to discounted tickets in standard class to entice them away from their cars. On the York line with GNE you can get free reservations if you do so by 6 or 7pm the day before - don't know if available right up until the train. But many if not most seats in standard class have reservation tags on them as the cheap advance purchase non-refundable, etc. tickets they buy come with reservations.

for the trips where your departure station is london, you should be fine, as that's where the train starts. get there early and as soon as the boards show you a platform number, head for the train and get yourself a seat. for the other journeys, who could say?

I've traveled the the UK 4 times, each time with a BritRail pass, and never made a train reservation for any journey. I never failed to find a seat, even when in a group of 5. I've traveled on weekdays, weekends, bank holidays, day trips, longer trips. I've been from Brighton to Inverness (though not in one day of course!) Now I admit I haven't attempted this at the height of the High season, but I think in June you will still be pretty safe "winging it" without train reservations. Most of the journeys have many trains a day so if you do miss one, you can still travel an hour or so later. That's the beauty of the BritRail pass, its flexibility.

Once exception might be if you want to take a sleeper train, though I have not done this myself, I believe I read somewhere that reservations are required for those.

Enjoy your BritRail jouiney, I have always loved it. Oh, and you can research schedules at the National Rail website - http://www.nationalrail.co.uk/