Question

4. What makes Mr. Dursley stop dead in his tracks on his way back from the bakery?

Why do you think Uncle Vernon suddenly decides to give Harry Dudley's second bedroom?

Answer 1

He stopped dead in his tracks on his way back from the bakery because he overheard people in strange clothing saying something about Harry Potter which sounded an awful lot like his nephew's name, and after a day of peculiar happenings even more evidence was pointing towards his worst fear.

He suddenly decided to give Harry Dudley's second bedroom because he was afraid the wizarding world would find out how neglectful and abusive they are towards Harry. With the swarms of letters he knew that Dumbledore and the wizarding world were onto them. It was not out of sympathy in any way, it was out of fear.

Answer 2

The Dursleys moved him because they were worried that Dumbledore (or whoever was sending them Harry's acceptance letters) had made it clear that they were aware that Harry was being kept in a cupboard. Shortly after they moved him, the letters reflected the change, even if they were still a bit sarcastic.

Step-by-step explanation: