The limits of my digital cameras are exposed. The filter is too strong to allow them to see through it at night. They do pick up an image when using an infrared light, but they'd need infrared floodlights to cover a whole room. I need to borrow some more sophisticated cameras, so I can decide whether it's worth investing in a better one.
Therefore, I continue to try to remove the IR-blocking filter from a camcorder. Without that, the CCD should be much more sensitive to infrared and might work with the filter in place.
The next challenge will be to do the same with a digital camera - although the small size of these won't make that easy!
I have not yet been back to re-photograph the old house because today is exceptionally wet and windy. On the full-size image, the 'hedge' is clear, with the wall embedded in it. However, I have to take pictures from several different angles to determine whether this was something worth investigating or just a trick of the light. If it doesn't appear again then I'll mark it 'artefact' and leave it at that.
With infrared, of course, it could be a trick of non-visible light.
I am in the process of butchering the Panasonic camcorder, but as I am expected to be sociable tonight I probably won't get the pictures up until tomorrow.