One of the excuses for recent increases in rail travel ticket prices in the UK is the cost of fuel:
Rail and bus fares are on the increase, in part because of fuel costs. In June, First Great Western blamed its second ticket hike this year on rising oil prices. A spokesman said that as the company ran high-speed long distance trains, rather than local services, "we are more greatly affected than other operators by increases in fuel prices".
However, the cost of fuel in Latvia is only 30% less than in the UK, which doesn't explain why train travel is 15 times cheaper there.