Siusaidh if Nominet auctioned off all dropped names instead of letting then drop, there would be no drop catching, it would effectively be a monopoly. I don't see it going that far, I hope at least. It is anti competitive because all dropped domains would only be available from source. The new TLDs reserved the "premium" names, or the obvious ones at least. It is too late for Nominet to follow that path, they are released out into the public domain already.
I agree with RobM regarding what one persons view of "premium" is. The value is what someone is willing to pay not what someone thinks it's worth. Take a look on ukbackorder, domainlore etc some great names available, especially on .uk for what I think are great prices. More food for thought is if the UK splits up, Wales and Scotland have their own TLDs already , if merkel get's her way N.I would remain under eu control. England would then require it's own specific TLD, which I assume Nominet would create.
Interesting times ahead, changes are coming I just hope they are not too drastic and are fair. I like the current system, not caught any mega name but there is a chance, once a new system comes into play I feel that chance will be even closer to zero if they choose a pay to play to favor the large registrars.