Hi All, daughter's mk6 rear number plate has lost a screw, and she's asking me what type of replacement she needs to get..... is it the self-tapper type screw or the one with a backing nut she needs to buy, Halfords have both.... thanks!  btw, she's not local to me so I can't investigate. 

Should be a machine screw on a Mk6.  They have a long threaded nut in the tailgate like this.

"Official" fitting should be as Tom suggests. Problem can be that when the car is first prepped when new, or if replacement plates are fitted at some point, the fitter may not use the captive mounting. 

I've had more than one experience, even on new cars, where they have ignored the factory mounting points and just drilled through the plate and into the metal of the tailgate and used a self tapper!

Over the years I've built up a stock of the various types of fixings so can usually deal with anything. You don't really know what you will actually need until you remove the plate entirely, though, and see whatever bodge lies beneath.

Fully remove the number plate and thoroughly clean the paint work behind it. Once dry refit the number plate using 'sticky number plate pads' very quick and easy to use. They can be placed over the hole(s) in the tailgate to stop water getting in.

EXAMPLE:  https://www.amazon.co.uk/STASS-XTRA-THICK-Adhesive-Motorbike-Caravan/dp/B0CJJTTP4W/ref=asc_df_B0CJJTTP4W?

 

 

You can get large sticky pads that are pretty much the size of a plate, they stick very well and securely.

Wash the area with soapy water then use alcohol wipes before applying.

I went away from sticky pads and visible screws ages ago, plate holders hide many sins and look tidier.

Great response! Thanks everyone for your advice👍 I've copied the thread on to my daughter for her to decide which option is best for her.