Q: I am currently 2 stone overweight and am a vegetarian. I would like to lose weight, but would also like to start out on adopting a calorie restriction diet, because I am convinced of it's health benefits. Could you give me any advice on where to start?
A: Best to start slow; because this is a marathon, in competition not with others but with your own genes and environment, rather than a sprint, you should develop the habits that will sustain you long-term. I take the hunger out of calorie restriction by eating the things our bodies were designed to function best on: lots of plant foods with occasional lean meat. But all plant foods aren't equal. It's turns out, happily for you and me, that the foods most packed with nutrition are the same one's least packed with calories. This means that these are the ones you can eat in unlimited quantity (without exploding) and still be safely calorie restricted. Of course I'm referring to vegetables and many fruits. (Not so with grains and legumes; with these you must be mindful of the calories.)
If you commit to eating meals dominated, if not monopolized, by these plants you should not have to battle hunger. Though temptations don't go away, at least they're rooted in something other than hunger (habit, mood, etc.) and dealt with accordingly. My personal eating regimen, which is one among several, if not many, used by veteran CR practitioners, is to eat two very large meals each day with no snacking: In the morning I have a huge bowl of many types of berries, apples (primarily peels) and 1-2 ounces of nuts; at noon or dinner I have a magnificent salad with many vegetables (1.5-2 lbs) with sparing application of dressing or generous if not oil-based. Since you are vegetarian, you should have no problem with the plant-centric strategy. I hope these thoughts were helpful.
Incidentally, at the outset spend a week identifying your "set-point", which will become the basis for developing your daily restricted calorie objective. Though 20 years old, I recommend Dr. Roy Walford's instructions in his book "The 120-Year Diet". 
One final point. To finish the marathon (especially with the slowest time possible), you cannot treat CR as a mere diet, this parenthetical thing that is going on in the background of your life while the real important stuff, the stuff in the foreground, gets your real focus and energy. CR requires, and deserves, much more than that. Some things by their nature cannot be parentheticals or incidentals in life; Mt. Everest, mastery of a musical instrument, leadership in your church or synagogue. These, in varying degrees of course, demonstrate passion, commitment, many hours of concentrated attention. Along a spectrum, with these on one end and a "diet" on the other, my point is that your CR practice, to endure, must be closer to the former than the latter.
Like all such things, there are times when you're driven by enthusiasm and times when more effort is required. Personally, I seek out opportunities to talk about CR (as here); I never turn down an opportunity to tell others how great CR is. By being a fervent CR evangelist, I've done more for my health than for that of anyone else (my convert list is not very long). I also stay in touch with other practitioners. Be sure to attend any CR conferences or other events, regardless of travel hassles; though not as frequent as they should be, they are great for getting new ideas and recharging your batteries. I revisit CR books and articles from time to time. I also try to follow new developments in health, which often provide CR insights. All these things serve to remind me why I'm doing CR, what CR offers that so far nothing else on the planet can.
Good luck.