1 meter by 4 meter raining wall

Hi guys I would value some help! I am a complete novice, but I have just finished work and I need to have a go.

Ok so my plan is a 1m high by 4m wide retaining wall, my garden slopes from top to bottom and is approx 24 feet below the house level.

The proposition I have is to use 3 x 1.75 meter high concrete fence posts and then slot in gravel boards 3x .31m and 1 x .15m high x 1.83m long boards.

The main question I have is that I an wqondering whether this will be strong enough to retain back the earth (MOSTLY CLAY)!

I could tip concrete down the back of the wall and tie it in if that helps but would hope that the boards are suffice to retain!

PLEASE HELP!

here are some pictures the first is my garden from the back door, the second is the area for the wall.

http://www.imagebam.com/image/8cae175511033

http://www.imagebam.com/image/faea065511035

no-one got ANY ideas on this.

Looks like I might have to take a stab in the dark!

In short it will eventually fall over.. prob after the first heavy rain..
Your better off doing a proper job and creating the wall in engineering bricks (215mm wide wall) with a decent 750mm wide x 300mm deep concrete footing.