I have been dealing with a guy on a business basis for over a year now. We get on very well, are the same age and always talk on the phone about non work related things every now and then and will be on the phone for 45 minutes minimum about friends, family, things we like on tv etc.

Long chats and good rapport, seriously increase the chance of both men and women finding each other attractive.

In the past when i have seen him i have always noticed him checking me out, he once commented on how my jumper matched my eyeshadow, which suprised me..

That could have just been a funny, quick witted or break the ice comment.

Once over an email conversation he asked me if i would miss him when he went on holiday.

Yes, it seems as though he's enquiring about how interested you are in him.

Face to face he is not as flirtatious as over email.

Flirting by e-mail is less risky and much more easy for men. Flirting in real life with women, has much more potential to go wrong, and leaves him unable to escape an uncomfortable situation (if that uncomfortable situation arises).

I think he knows i like him but not sure on how he feels.

By what you say, it sounds as though he thinks you might like him, but is trying to find confirmation, like being flirtatious and asking if you will miss him.

Recently we went out for a lunch with some other colleagues. We all get on well and have a good laugh, his 2 colleagues even made a "joke" of how much we have in common, he was acting more jokey than normal, even mentioned his ex girlfriend but no current one.

He is bound to act jokey with his colleagues around. People tend to show off a lot, but also act jokey to break the ice or because they want to hide that they are nervous.

He also took a picture of me on my own on his camera phone, much to my embarrassment.

Probably want to show a picture to his friends, to get their approval. Other reasons you take photos on your mobile are to show off (look at how good looking my girlfriend or potential girlfriend is). Or when you are having a bad day, just flip the phone and look at a photo of you and think I'll be having a good time with her later, so I can forget about this bad day.

Are these signs he's keen?

I must say, you haven't said anything that is conclusive to me yet. There are a few bits where he has maybe indicated that he might be attracted to you.

Im not sure what to do as don't want to ruin anything but i'd rather know if he is not interested. The lunch was his idea and he had tried to organise it ages ago!

It does seem as though he wants to spend plenty of time with you. You have good conversations and he is probably thinking the same thing, "I don't want to risk losing her by making a move".

I don't know how far you want to take it yet, but I would say if you need to allow him to get close to you at every opportunity. If he makes attempts to get physically close to you or even touch you, don't discourage him and make sure you reciprocate shortly afterwards.

Though don't go over the top and touch him at every opportunity because you might make him jumpy. You need to touch him about the same amount of times he touches you. By touching him I don't mean grab him by the crotch, but just light touching on the arm, shoulder, hands to start with.

When you sit near him try and gradually move closer and open yourself up. You may start the conversation a fair distance away and with your upper body turned slightly away from him. But gradually move close, open up your upper body to him and even uncross your legs and have them almost placed at either side of one of his legs (not too close but to signify you have problems opening up to him physically as well as socially).