There is a certain amount of incorrect information here. If you fly BA from an external destination, as I did from Toronto, they ask how many carry-on items you have and they ask whether you are transiting through Heathrow, and they tell you why they are asking. If you are staying in England, you are allowed to carry two items because North American rules apply. If you are transiting through a UK airport, and definitly when you leave a UK airport, then European rules apply and the one bag limit is enforced. They do tell passengers this on embarking from wherever - if they don't they are being remiss. Anyhow, it is on their website.
This carry-on rule is Europe-wide. It is not limited to BA and England. If you check the history of this new system, you will see that it was decided by the European Union in consultation with the airlines and the security people amongst all member states. Every member of the European union is expected to enforce this carry-on baggage regime. Implementation of course will vary over time and place - this is not unusual. But sooner or later all will comply, or the system will be changed.
The ostensible reason why this is happening is because for the longest time the airlines have been trying to limit carry-on baggage. It is a huge nuissance for them. With the added security arrangements as a result of the recent intelligence about planned co-ordinated terror attacks, the onus on the security people to search carry-on bags became very heavy. Those airports simply don't have either the space (because of duty free shopping which pays rent) or the people (which costs salaries) to handle this efficiently, therefore reducing the carry-on allowance was the option they selected to keep the security operations manageable and costs down. Remember also oil prices have increased alot, so the less weight they need to carry, the less they pay for fuel.
BA has also vastly reduced the checked baggage allowance,s and imposed huge penalties for exceeding the reduced new limit, hence between this new policy and the reduced carry on allowance, anyone who wants to travel outside these minimalist limits will pay through the nose. This has nothing to do with security - it is completely commercial - a fare increase through the back door to pay for rising costs. Not all airlines in Europe have done likewise for checked baggage, but they are all wathcing the BA experience with keen interest, so there could be more widespread grief to come.
What is most unsatisfactory about all this is that they have not correspondingly improved the conditions for handling checked baggage, nor changed their liability exposure, hence the customer ends-up carrying all the risk and the cost. This is a real problem all airline companies traveling through Europe need to face, otherwise people who must carry more than one bag with sensitive equipment will start avoiding Europe altogether.
Heathrow also needs to drastically improve how they enforce the policy. It is inexcusable that they allow passengers beyond the check-in counter with illegal luggage and then force them through the whole queue again. Anyone experiencing this should write a letter to the Chairman of the British Airports Authority, the Chairman of BA, and copy it to all the main newspapers in the UK and abroad. This may wake them up.
As for CDG-Paris. We were through there last November. We found it more than usual a complete administrative mess in almost every conceivable respect. We ran into a staff member of Air France incapable of using their own reservation system, their baggage handling is a total disaster (they lost our bags for two days), their electronic notification system for flight gates often leaves out your flight and gate (as happened with ours), and as usual the airport is dirty, the signage is poor, it is vastly over-crowded, some of the booths of the immigration service are dimly lit and cramped, so they can lose documents placed in front of them causing near panic (happened to us) - really a place to avoid if at all possible. To their credit, when I outlined all of this to Jean-Cyril Spinetta, the CEO of Air France (yes, you get action by starting at the top), several months later I received a letter apologizing for the inconvenience and a credit of 5000 Frequence Plus points. So at least they aren't insensititive.
These are not good times for travelling photographers with substantial gear. Something needs to be done to sensitize the European policy makers at the level of the E.U. about how all of this is not suitable and therefore not acceptable. One can make photographs in many parts of the world other than Europe, and this needs to be impressed upon them - it is a big negative for their photographic tourist industries. Maybe they care, maybe it is beneath the radar screen - we won't know until it is really put under their noses at a very high level.