Phil,
In my experience it's totally hit and miss, but I would try phoning around at precisely the 11 month window. I don't claim to understand how it all works, but it seems that the travel agents/tour operators, etc, each get allocations of discounted prices which increase in steps. So, for example, each will have an allocation of really cheap seats, then slightly more expensive, then a bit more, and so on. Obviously the cheapest of all are going to go first.
When we booked our flights for December, friends got seats (Virgin) for about £350, but by the time we started phoning around a couple of weeks later, the cheapest we could get was around £415 for the same flight. They got theirs from Flightbookers, but the cheapest they could do for us was coming in at close to £600. We eventually got ours from Expedia. So I do think it's important to phone around because, whilst one agency's cheap allocation may be gone, another may still have some. We've also found that we've had better quotes by phone than we have online.
We have used Flightbookers, Expedia and Virgin Travelstore (who are a
travel agency and can book holidays and flights for all operators, not just Virgin).
