A bendy left elbow RHD golfer

I am a 24 handicap and having received some great advice previously about putting, I am hoping that someone has a drill to correct my tendency to bend my left elbow too much, and early, during the back swing. Since I am getting on a bit, I have lost some flexibility in my body, but I should be able to keep my left arm straight
During a round I will probably hit about a dozen or so shots fat, usually with the longer irons, due to this problem, so any drills or training aids that help me to remember keeping a straight left arm will be greatly welcome.
Also, at what point during the downswing should I be rotating my hips towards the target? Should I start rotating and then start the downswing, or does the downswing start before the rotation?
Thanks once again in anticipation of some great replies.

regards

Lester

Actually the best advise I heard on this area, was from here, I think Greg gave it talking about extension, but it has the added benifit of keeping your left arm straighter. Greg correct me if I quote you wrong on this, but at address and has you swing, lightly pull with your right hand as if you are trying to get the club free from the left hand. Should add some distance to your shots as well, more extension wider arc and a straight left arm without being stiff, all good things, excellant swing thought.

Addon: OK I found it, here is the thread I was thinking about, now you can read it from the horses mouth...lol...so to speak
http://www.golf-tuition-online.com/g...y-achieve.html (Good Extension and a way to achieve it)

Thanks GoNavy, excellent swing thought, I will try it out this week. The thread link was very informative also.
regards

Lester