The fishing party photograph was published on the river keeper's website some time ago and if I remember correctly was taken in the 1890's.
There are weirs and fish pools above Alport and until the recent efforts to return the river to it's natural state, fish were raised in pools for restocking purposes. These would I assume be both Brown and Rainbow Trout.
The "red" in the description of fish would refer to the colour of the flesh, a result of diet and always a pleasant thing to see when compared with the rather pale flesh of some fish.
In case it is in doubt I have no problem identifying fish, from high or low vantage points; Rainbow Trout, in the water are identified more easily by features other than external colouration, which itself can be very variable. The naturally breeding Wye Rainbows have additional identification features (as compared with stock fish).
Back to mine drainage.