It may be that there has been no change to the airspace structure and yet aircraft are flying in different places.
Some reasons for this include:
Aircraft normally take off and land into the wind
This can affect which direction aircraft approach the airport from. For example the UK’s prevailing wind is from the southwest. But if the wind comes from the east and is above a certain speed then you may see more aircraft on different routes on that day.
The number of flights normally increase in the summer
As the UK economy grew in 2014, that summer was busier than the summer before. When there is more aviation traffic, the decisions air traffic controllers take in order to tactically vector aircraft into and out of airports in the most efficient way (determined by traffic levels and the weather) change.