As nobody else has replied here is my contribution.
First I have to say that the market for silver plate is not very good and may be very dependent on finding someone who wants the set. In addition a 141 piece set is going to be far too large for most people today. My feeling is that a valuation based on about £3 per item would be fair. That gives you about £420 or 480 euros. However I think you should allow a fairly wide band below and above that figure, say 300-600 euros.
There are a couple of relatively large M&W sets on eBay at the moment (220877686575 and 320776560951). You might like to see how they end.