That pre decimal system always confuses me. I still have a littleI chart to look at to figure out it. Not sure why anyone would have slabbed that particular coin and paid for the special label fee, but if you got it for a decent price, good. I have a couple world coins in the same situation.
Could be worse--over in Jersey it was 13 pence to the shilling for a while! Here's a handy table with all the conversions they had to deal with...
I concur. That coin is in the grey area where you have to make a decision whether to melt or not, because as a collectable item there would be virtually no interest. All the war years are very common (1914 is slightly better) and particularly in this condition - I am currently looking at a pile of a few dozen said items. The decision of whether to scrap or not usually boils down to whether you are going near a place that buys in scrap silver.