I passed through Brighton today and there was a big revenue protection effort going on. Oddly though they sealed off the East and West Coastway arrivals from the London platforms and didn't allow any passengers to change trains the platform side of the barriers - we all had to leave the barriers and then re-enter. With a full load of passengers coming off my train being funnelled through a few gates I very nearly missed my connection. Is this normal practice? Is there a particular problem with fare evasion from the coastway trains onto London ones? It just was a fairly terrible customer experience.
Though some changes don't require leaving the platform you're on - virtually every East Coastway train uses the 7 and 8 island; but 7 is also used by some London services.
I don't know whether West Coastway trains ever routinely use platform 3 - but that would also allow access to London trains without having to go to the end of the platform.
East Coastway's Seaford branch has always been pretty bad for ticket less travel. If memory serves it might only be Lewes that has barriers.
Yes - Seaford doesn't have barriers, but Lewes does. (And I'm pretty sure the minor stations along from Seaford have no barriers either.) And coming from Seaford you can interchange at Lewes (inside the barriers) for London-Eastbourne trains, which of course serve some barrierless stations.
Interesting about the blocks at Brighton - I've never seen any in probably dozens of journeys in recent years. Mind you, although the main gates onto the concourse are usually in use, if your ticket is spat out of the gate the attendants generally let you through without bothering to look at it!
Last time I broke my London-Brighton journey at Hove (making a diversion en route), expecting my ticket to work the gate but be returned; but the gate wouldn't open. The guy had a good look and then said I was trying to use the wrong ticket (ie the Brighton-London return coupon) - though of course that should work too, but maybe he saw I'd arrived on a train from London not from Brighton. So I apologised and dug out my other (outward) ticket instead to show him so he could let me out, but without realising it gave him another return half [I'd got the pairs of tickets divided up wrongly with my travelling companion]. So he looked at that one (which was identical to the previous "wrong one"), pronounced himself satisfied, and cheerily opened the gate. Which all goes to show that gate staff checking tickets manually are not always bothered, or fully awake.... Maybe when there's a revenue check they're more careful; but I get the impression that routine manual ticket inspection is pretty cursory - though perhaps not cursory enough to fail to act as a deterrent.