Hi!
There are a lot of Members on this forum who are indeed very knowledgeable about Daimler records, codes, manufacturing statistics etc., who will, I am sure, provide possible interpretations of the Order No. you have on datacard.
I looked just briefly - indeed on 190SL forum there is no dealer list codes. By some mentiones in the posts you see that some of the dealer codes match those of W113 we have here (you have a fairly late car (1961), so this may be possible). But I am not sure if there were no alterations between 1961 and 1963 dealer codes (end of 190SL and start of 230SL) to nail if 541 is for 190SL Iceland, as it is for W113.
Could it be a demo car? Cancelled order? Was it a favourable tax/duty arrangement - you ordered in Iceland, but took it somehwere else to avoid duty being paid - we know such cases in some territories.
Also: what I have learned about classic Mercedes is that when you say "never" or "always" you need to really be sure of that...
By the way: I have just come back from my friend's who have a house near Castellina in Chianti. I envy you - no matter where you move from your place, within a couple of hours you bump into a motoring history at its best - from Pontedera to Maranello...