I have just returned from Poland where at the EAA conference there was a whole session on Valetta, its implementation (or otherwise) by signatory states. This included a paper by someone who was part of the initial negotations, as well as views from colleagues throughout Europe on the effectiveness of the convention.
Some points relevant to our discussion, that arose as I remember them...
"Qualified and specially authorised" does not equate to "Chartered or Licenced" - a deliberate vagueness of phraseology in the convention document.
There was considerable discussion about the wording of section iii in respect of metal detecting. The original wording was stronger but was vetoed by the UK representative as it was felt that the convention could not be ratified by the UK parliament with the original wording.
Valetta and PPG16 were quite parallel processes, which happened more or less at the same time and so there is a lot of one in the other. So similarities are not accidental, they were intended back in the late 1980s.
A couple of general points...
There are numerous subtle but important differences in wording between the official English-language and French-language versions. Such as, for example, the requirement for full publication (much stronger in the French version).
There is a lot of divergence between the practical implementation of Valetta in the UK (very advanced) and with other signatories of the convention. Others have chosen different ways of implementing it in view of their cultural, social and economic situation.
The full (English) text can be found
here.
The full (French) text can be found
here.
The table on this page shows who are Parties (P) and Signatories (S) of treaties relating to Culture, the Valetta convention is No.143.
I hope this is useful.