nailing mini stonewold roof tiles

I am about to tile my single storey extension with Redland mini stonewolds. I have heard different views about nailing the tiles, from every third row to be nailed to just the verge tiles to just the occasional tile requiring nailing.
I have had a look at the Redland zonal fixing guide and this basically states that each tile should be twice nailed, but they do not require clips!
I was just wondering what the pro's would do in this situation. As stated it is a single storey extension with the ridge at about 4 m high. Pitch is 21.5 degrees. 11 rows with 14.5 tiles per row.
Any thoughts appreciated.

These tiles are roughly 5Kg a piece. It would take quite a breeze to shift them. Unless your roof is in a particularly exposed location I wouldn't have thought you needed to do more than every 3rd course, expecially with lowish pitch you're using.

A few years ago I went to buy some tile clips as recommended in the Marley fixing guide and was practically tarred and feathered by a shop full of hairy-ars*d roofers for suggesting such heresy. Guess what: the only fixings they used were gravity and cement to fill the gaps at the verges & ridge.

With these heavy concrete tiles the only place I've ever felt the need to use additional fixings is on cut tiles around sky-lights and edges. Fingers crossed, nothing's blown off yet.

in exposed areas its advisable to mechanicaly fix every tile.

it used to be the case when it was common practise to nail/clip every 3rd row , nowadays its usually specified that each and every tile is clipped and or head nailed.
including eave and verge clips. makes it more difficult to do any repairs though .

Southampton is on the sea, wind howls down the Solent... I'd say a minimum mechanically fix all perimeter tiles nail and clip. (including verges)plus alternate courses nailed. this as a minimum.

but it might be in your favour to follow Redlands spec.

Basically the question you need to ask yourself is this.

Do you want the manufacturer guarantee for the roof covering or not?

If not, fix it however you please.