Antique country house oil painting ID help

The locality reminds me of Glengyle House on Loch Katrine, where I spent a holiday with friends some years ago.  It might be a painting of the original house which was reputedly built by Rob Roy McGregor? It does seem to be a view across a Loch.

I can't tell you anything about it, I fear - I doubt that it was made by a well-known artist: there are one or two clues to that, but it's a pleasant painting, and the building itself is well-painted - it's the rather deliberate framing by trees, including one that looks as if it was placed there only to address that obvious compositional problem posed by that framing, plus the execution of the trees themselves, that suggest to me that this is the work of a competent amateur.  And absolutely none the worse for that.  Is that damage, in the tree on the left?  Hard to tell at this resolution, but if it's meant to be a highlight it doesn't work - it looks like either the application of plain white paint, or an area where the picture was too aggressively cleaned. It could do with a general wash and brush-up - i.e. the attentions of a conservator/restorer.  The name looks like William, but you'd probably need to remove the painting from its frame to read the rest of the signature.  Date - I'd guess at mid-nineteenth century.  I think it could benefit from a sensitive bit of conservation work, and suspect you'd see a wider range of colours and tones if it were cleaned. I wouldn't come to any firm conclusions about the roof tiles - blue slate makes for a rather cold look, it wouldn't be surprising if an artist chose to warm the picture up a bit - because those trees are dark and cold - with a touch of Light Red or whatever.  Not saying he did - just that such details may not be quite accurate.  

Is there anything at all on the back of it?