1. Research Online: Use search engines like Google to look for strip out contractors in London. Visit their websites, read reviews, and check their portfolios if available.

2. Ask for Recommendations: Reach out to friends, family, or colleagues who have had similar work done in the past. They might be able to recommend reliable contractors based on their experiences.

3. Check Trade Directories: Look for contractors listed in trade directories or industry associations. These platforms often list accredited professionals who adhere to certain standards and codes of conduct.

4. Get Multiple Quotes: Contact several contractors and request quotes for your project. Make sure to outline your requirements clearly so that you can compare the quotes accurately.

5. Verify Credentials: Ensure that the contractor you choose is properly licensed, insured, and has relevant certifications. You can verify this information by checking their credentials and contacting the relevant licensing authorities.

6. Ask for References: Don't hesitate to ask potential contractors for references from previous clients. Contact these references to inquire about their experiences working with the contractor.

7. Visit Completed Projects: If possible, visit some of the contractor's completed projects to assess the quality of their workmanship firsthand.

8. Communicate Clearly: Once you've selected a contractor, clearly communicate your expectations, timeline, and budget. A reputable contractor should be transparent and communicative throughout the project.

By following these steps and conducting thorough research, you can increase the likelihood of finding a reputable strip out contractor in London.