Thank you very, very much indeed for this. I love this song, and so does my mother, and finding out the full lyrics and where it is from has been wonderful.
I've been rather amazingly busy at work the last day or so, so was not able to respond properly until now (not enough computer access), or I would have responded more fully earlier.
I'm absolutely amazed at all you found.
If it's all right with you to use your research like this, I'll update my page sometime in the next week or so with the information you've found. I'd like to add your MIDI as well (again, if that's all right with you).
The tune is exactly the same as Mum's (any difference in my transcript is due to my own low level of skill as a transcriber).