I'm no Carol Vorderman but I don't think buying half as many tickets makes your doubles odds. If you buy 1 ticket then your odds are 1 in 14 million. If you buy 2 tickets your odds are 2 in 14 million, not 1 in 7 million.
but if he normally bought 2 tickets and dropped down to 1 ticket since the price went up to £2 then his chance of winning would be halved

I was all
the first time I heard this too 