Thank you to all who commented on the new blanket. I received a couple of comments asking how I went about joining the granny squares together as I was obviously not waiting till I'd finished making all my squares before doing so. The answer is... join as you go. For me, it's the best way. It's quick as it eliminates an additional (and time consuming) step in the blanket making process. I like the effect as it keeps the blanket smooth on both sides (unlike the thick seam you get on one side when crocheting completed squares together), and it stretches the corners of the squares together nicely too so there should be no need to block them. One possible downside is that you need to be reasonably relaxed about how you position the squares as you can't lay out all the completed squares before deciding where to put them. Joining squares using this method is possible when there are regular chain spaces in the previous round, traditional granny squares are therefore ideal.
I thought I'd illustrate my method with a few more photos. I'd hesitate to call it a tutorial as it's perhaps a bit rough and ready compared to other tutorials out there.
Next I pick the first square (bottom right above, though you can start from either end) and start to crochet the final round.
I have to say, I don't usually place the blanket so neatly on my knee when I do this so sometimes my tension is a little variable but it doesn't seem to be significant enough to affect the overall look of the joins. The first time you do it you feel like you need another hand to hold everything together, but you'll soon get the knack.
In a later post I'll list the yarns I'm using. They're all Stylecraft, a mix of Special and Life.
Blanket inspiration came from Pixie's beautiful blanket (here) and ViolaViola's lovely blanket (here).