Thinking about this subject it occurred to me that this should really be a subject of a Risk Assessment. This is because of possible action or in-action causing injury to members.
I looked at the NYM 100 Risk Assessment but it doesn't go into any detail of First Aid. Maybe a section on LDWA-specific injuries is needed?
Possible risks would appear to be (amongst others)
1) Infection of a blister
2) Inappropriate treatment of a blister
3) Ignoring blister leading to later complications
The most difficult area appears to be around 'What IS the appropriate treatment of a blister?'. I remember a few years ago on a First Aid course being told to drain a blister but as they pointed out, First Aid advice is continually updated, so one has to keep abreast of the situation. Googling several First Aid training websites would indicate that currently it is NOT recommended to drain a blister, but several go on to say it SHOULD be drained if it looks as if it is going to burst anyway. I think most advice is based on the implicit assumption that the the activity causing the blister has already ceased, but of course with LDWA members this is not the case so perhaps special advice is needed for us. Bearing in mind that most walkers would continue with a blister unless it has become too painful or raw, then it would seem appropriate to drain it as soon as possible as it's only going to get bigger and burst later if the walker continues. Only if the walker retires would it seem appropriate to NOT drain it.
It would appear important to clean the sorrounding area, to use a sterilised needle to prick a blister and to apply iodine or similar. First Aid advice suggests pricking the blister near the edge and allowing it to drain, but in my experience if it's under thick skin then it's best to go for the middle but inserting the needle at a low angle to avoid the point making contact with the otherside of the fluid-filled cavity. Often several holes might be needed and pressure is nearly always needed to expel the fliud. The relief can be almost immediate once drained. Once drained, a Compeed can be applied. It's no use applying a Compeed to an undrained blister if the walker intends carrying on.
It would seem that First Aiders need special training in the use of Compeed and in the stubborness of LDWA walkers. Both would seem to defy common sense. The most important thing about Compeed is that once applied, they should be allowed to fall off in their own time (several days at least) and not forcibly removed.
The most important thing though is to prevent blisters in the first place. This website offers the most useful information that I have found so far
https://www.skinsight.com/skin-conditions/first-aid/first-aid-blisters. Interestingly, they recommend acrylic socks as cotton or wool socks can become misshapen during use; this matches up with my own experience, as since using acrylic socks I rarely get blisters. Discussion about 'wicking' socks is a waste of time, as once a sock is wet, it's wet and nothing can be done.
I think the advice about using talc is probably useful for 'dry' activities, but inevitably feet get wet on most LDWA walks which reduces talc to a sodden cream.
Compeed should be applied at the first sign of pressure and not wait until a blister forms (which can form as soon as a few minutes after noticing the pressure). Anybody who allows a blister to get so bad so that it 'de-roofs' (loses the outer layer) before starting treatment should almost certainly withdraw as Compeed on raw skin isn't going to help then to continue.
I did visit the Johnson & Johnson Compeed website
https://www.compeed.co.uk/footcare-centre/compeed-blister/how-to-apply for advice but it has nowhere the level of detail that I was hoping for.