Imagine you have a toy that you really like, and you play with it all the time. Then, one day, your mom says you can't play with that toy anymore because it's too old or doesn't work right. You don't want to stop playing with it, so you get upset and argue with your mom about it.
Now, let's pretend instead of a toy, it's a school. The school has been around for a long time and is really important to the community. But the government thinks the school is too old or doesn't work right, so they say it can't be used anymore.
This is what happened in Thoburn v Sunderland City Council. The government said that an old law called the European Communities Act was more important than newer laws made by the British Parliament. This meant that some local government decisions couldn't be made without following the European laws, even if they were out of date or didn't make sense.
The people who disagreed with this sued the government, saying that the British laws should always be more important. They didn't want to follow the European laws if they didn't agree with them.
After a lot of arguing and going to court, the judges decided that the British laws should always be more important and the European laws couldn't overrule them. This meant that the government couldn't force local governments to follow the European laws if they didn't want to.
So, in a way, Thoburn v Sunderland City Council was like a big argument between the government and the people about which laws were more important. And the judges decided that the British laws won.