Life has been tough for those managing FF programs in all airlines. The reason is that the lowest economy fares have to match the low cost carriers like EasyJet and Ryanair. Before the majors changed their schemes, a person flying in Economy for 50 pounds/$/whatever got the same FF credits as someone paying literally 10 times as much. What BA, LH, Swiss and others have done is to reward people who give them the most money, not those who fly the most with them. Booking via the web has nothing to do with this. If you are flying a fare that does not earn tier points with BA (or does not earn full mileage with LH and others) you will find that another higher fare exists for the same cabin. Personally, I find this normal.
I find it totally acceptable that a person who flies 50 times a year, but spends a total of $10,000 (without airport taxes, etc.) gets less credit than a person who flies once on BA's obscenely expensive fares to the West coast and pays $12,000. The latter is the one BA wants to reward. It has a side benefit that they already have lounge access for their C fare. This has to be part of the cost/benefit equation for the airlines too.
Back to the original question, BA has revised the scheme somewhat since the change a few years back. It is once again easier to gain tiers flying from Switzerland to the UK if you are a Swiss resident. Silver is currently 400 points for Swiss residents. I might be mistaken, but I think it is 600 at the UK end?
Bottom line: pay more money, get more tier points.
Momo