What is the average train speed in the UK?

The average speed at which trains in the UK travel is between 60 and 65 mph (between 95 and 105 km/h). On main lines they can reach a speed of 130 mph (210 km/h). The actual maximum commercial train speed in the UK is 186 mph (300 km/h) and 249 mph (400 km/h) for Maglev trains.

Is the speed of trains increasing?

Yes, thanks to technological developments it is possible to make trains travel faster. The very first trains only reached the speed of 23.6 mph (38 km/h).

What is the fastest train in the world?

When we want to know the fastest train in the world, a distinction has to be made between a train on wheels and a train on magnetic rails. The fastest train on wheels is the French TGV150, and reaches a maximum speed of 355 mph (574 km/h). In 2027 Japan will introduce the L-Zero Maglev train, where they are already reaching test speeds of 362 mph (581 km/h). This is not a train on wheels, but on magnetic rails. 

See besides average train speed also: 
Average Cycling Speed
Average Bike Speed
Average Speed of a Plane
Average Walking Speed