Thanks for your replies. Did you get an official diagnosis? I have a meeting with his teacher coming up and will need to discuss this with her.
Last night it took 2 hours for him to write one sentence on his project and then once I picked up the pen and he dictated it to me, he formulated an answer to the question in no time at all. (Turns out the dictaphone I bought is faulty so I need to replace it).
He also needs a lot of encouragement. I think I'm losing my mind. He's at the stage where he's getting little to no free time at home when he has writing tasks to complete and all that happens is we both end up frustrated and unhappy.

He is also learning to type (at a rate of knots - I'm extremely jealous) but I'm wondering why typing helps? Don't you still have to get the information out?