Nothing to do with Jehovah or JWs, its about "we won the war"day in the UK, officially known as Rememberence Sunday and even Poppy day.
Initially it was a good charity that raised money for disabled ex-servicemen who could no longer work after the First World War.
It become somewhat redundant to a certain extent with the advent of the Welfare State, though it still does a lot of good for servicemen with the money raised.
Many people however, see it also being used as a Political tool to Glorify and Romantisise war and ensure a continuing supply of cannon fodder, along with an acceptance of Britians version of invading Poland in the Middle East.
So, firstly the Gruesome Evil is War, (as in WW1 etc, not a Spiritual war), whilst I consider the word "necessary" to be highly debateable in regard to the majority of wars, thats not what the Proverb is about,
Now the Axeman, he is Britian itself, his axe is the military forces.
So, the first part means both a literal man who is employed as an executioner to behead criminals, its necessary according to the laws and customs of the day, whilst evil enough that most civilised countries have abandoned such, its a dirty job, but somebodies got to do it, and you would be a sick man if you were so proud of your job you would boast to your Children about your work and let them be corrupted by getting them to see and be touched by the dead mans blood, rather, you wash it off so you keep your children clean, innocent and to hold you in a higher regard than they would if they were aware of this most gruesome of your duties.
The Proverbial meaning of the first line however is that whilst it may be necessary for a country to go to war, war itself is a dirty evil thing, its a dirty job, but somebodies got to do it.
When I was young, I used to think of War as a Spitfire doing a gracefull victory roll across a summer blue sky whilst a hidden orchestra played a suitable stirring arrangement such as "633 Squadron".
Now however, I think of innocent children running down the burning street on stumps because their feet have burnt off.
Now, Iam sure you must be able to work out who the Proverbial "Children" are by now?