Photos
IO540 I have to take issue with you even though you are a wise chap.
Aerial photos in the oblique field can be a very worthwhile activity if you are geared up for it but it is not cheap to set up.
Nowadays with professional digital, image stabilised, zoom, wide angle and telephoto lenses, the results can be better than the previous results from traditional film cameras.
Of course we are not talking full or half plate cameras but it is no longer necessary either.
Image gathering is still developing and merging with computing in some areas. The main problem is that there is quite a bit of competition in UK.