Museum Boss Looks at Metal Loot in a Field

What is the evidence used in what the British Museum unjustifiably calls 'citizen archaeology' (sic)? Museum boss looks at metal loot in a field...

....while trampling on the sherds.

This is the essence of the problem with doing archaeology by proxy through the filter of a metal-detector-equipped collector. What we see happening in this photo is an archaeological site being stripped of the most diagnostic artefacts (archaeological evidence) on the grounds of the type of material they are made of (non-ferrous metals) while all the rest - by now largely bereft of that body of evidence - is left unrecorded in the field. That's not 'citizen archaeology' PAS-record or no PAS-record, it is knowledge theft.