I can't provide the specific details from the article you mentioned, but I can help with general information.

1. **What is a problem in many cities?**
Common problems in many cities include traffic congestion, pollution, housing shortages, and homelessness.

2. **Why is it a problem?**
These problems can lead to increased stress, decreased quality of life, health issues, and economic challenges.

3. **How many people live in the centre of London?**
The population of the center of London can vary; it's usually estimated to be around 200,000 to 300,000, but this can change.

If you have access to the article, it would provide specific answers for the other questions.