Mushroom insert securing bolt

[voucht]

Hi,
I know that in the UK, you have to put a bolt on the side the front upright in order to stop the mushroom insert tu turn and secure it. I don't have to do that here, but I really like the idea and I'm going to do it anyway. But I'm not really sure where to drill.
Where is best place for this bolt? what size shpud it be? (I was thinking about M6, as I have a M6 tap)?
Any advice (and picture to illustrate:) ) are welcome.
Thanks.

[SeriesLandy]

I used an m6 Allen bolt to start with but now it's a stainless hex bolt.
With regard to the hole its in the most rearward part of the upright in the centre.

[K4KEV]

Here is where I put mine, m5 self tapper with thread loc
http://www.haynes.co.uk/forums/showthread.php?t=4493&page=55

[voucht]

Thank you for the replies and the help :)

It's done! I used a SS M6 bolt with a lock washer.

https://farm6.staticflickr.com/5575/14968883582_f5682e37b7.jpg (https://flic.kr/p/oNKrzG)2014-08-19_13-06-09 (https://flic.kr/p/oNKrzG) by Voucht71 (https://www.flickr.com/people/99498333@N06/), on Flickr

https://farm4.staticflickr.com/3887/14969227685_ca6a0ca237.jpg (https://flic.kr/p/oNMcSv)2014-08-19_13-47-53 (https://flic.kr/p/oNMcSv) by Voucht71 (https://www.flickr.com/people/99498333@N06/), on Flickr

Thanks again.
Bye.