My rights
If you refuse to be stopped, the police can use reasonable force to both stop and detain you so they can conduct a search. You shouldn't walk away. You do have a number of rights that will protect you during and after you've been stopped or searched.
The police must have reason to suspect you
If police are searching for drugs, weapons or stolen property, they must have a reason to suspect you (such as a general description, your behaviour, or other intelligence) before they can search you. If they do not, they should not search you.
Except in cases of suspected terror