I cleared the watertower a few days ago, and saved just after entering the West Tower.  Given the difficulty I had with the East Tower - well, less the difficulty, more the length of time it took to get through it - I was expecting the West Tower to take an absolute age to complete.  In fact, it was pretty simple and disappointingly similar to the East Tower (though the route through was significantly shorter).

After opening the main gate, massive plot things occurred.  I am guessing that I won't be able to save the game after this point, so I'll have to complete it in one go.

More than once every two months?  Oops.

So, a recap.  I have managed to lead Yorda to the main gate, from where we should be able to escape.  However, her mother - or at least someone pretending to be - has appeared, and closed the gate in front of us.  I have battled many shadow beasts, and worked out that the most effective way of doing this is to go and stand by the portal they drag Yorda off to whenever they capture her.  In fact, the combat, which previously annoyed me and I felt wasn't needed in the game, isn't much of an issue any more, although its presence still worried me and stops me spending too long when exploring.  If you leave Yorda for too long, the shadows come back, and then it's a race back to save her.

After the gate shut, I traversed through a number of stunning locations - including one with a huge windmill which I had to climb - until I was able to run along the castle walls to the East Tower.  In this tower were a number of large circular windows, and I quickly worked out that the aim was to open each of these by lighting torches underneath them.  Working out what I had to do was the easy part; working out how to do it took a lot longer.  I had to pull Yorda through the doorways and around the walkways, finally finding myself out the back of the tower with some stunning views across the chasm to freedom.  I managed to finally open all the windows, sending a beam of light across to the main gate, causing half of it to light up.  A pretty big indication that I need to do the same on the other side.

Getting to the other side was pretty difficult though.  Much of the effort was spent around a huge waterfall area, where I had to jump on and off a turning waterwheel in order to close the sluice gate.  Yorda was no use at all during this part, with her slow running and refusal to jump up to ledges even with me extending my hand down to her - the game couldn't position her correctly.

I managed to get through this section, playing basketball on the way, and am now at 'the watertower', which appears to be named after a very small ornamental part of the level.  I think once I'm cleared of this, I'll be able to go to the West Tower and make the main gate open up again ... but that may take a while.