Here is a list of some leading national suppliers of marine self-tapping screws in the United Kingdom:

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Leading Suppliers of Marine Self Tapping Screws in the UK

1. Screwfix

   • Website: screwfix.com
   • Offers a wide range of marine-grade fasteners, including self-tapping screws.

2. Fastenright Ltd

   • Website: fastenright.com
   • Specializes in various fasteners, including marine self-tapping screws.

3. Bahnson

   • Website: bahnson.co.uk
   • Provides marine hardware, including robust screws and fasteners designed for marine environments.

4. Wickes

   • Website: wickes.co.uk
   • A home improvement retailer which stocks marine screws suitable for various applications.

5. The Screw Company

   • Website: screwcompany.co.uk
   • Supplies various screw types, including marine self-tapping options.

6. McFeely's

   • Website: mcfeelys.com
   • While based in the U.S., they ship to the UK and offer a range of marine screws.

7. Dura Fasteners

   • Website: durafasteners.com
   • Focuses on quality fasteners for marine applications.

8. Axminster Tool Centre

   • Website: axminstertools.com
   • Offers a selection of marine-grade screws among various woodworking supplies.

9. Toolstation

   • Website: toolstation.com
   • Provides a range of screws and fasteners, including marine-grade options.

10. J P Nuttall

    • Website: jpnuttall.co.uk
    • Supplies a variety of fasteners specifically for marine and industrial applications. ```

Please verify the offerings as availability and product lines can change.