I Know the ending of this Bayonet.........At the time the OP was asking for information, I contacted him, as this and others were his Father in Laws, the mother in law had insisted they go for auction rather than a dealer.
Brian sent me a list of the lots etc and I sent a detailed price guide to him regarding some of the Lot numbers that he sent me, unfortunate the auction house wouldn't take any notice of Brian, as I advised him to place a few reserves on some of the collection etc.
Although the auction did go in his favour with some items.
The one in question (The Bush Bayonet) went for £500 not sure on the buyers fee but probably 25% ....... He sent me a PM and thanked me for my guide price's etc.
I was told the buyer was approached in the auction and offered £800........
A lesson for us all, may sound morbid but putting a price tag on our treasures would certainly help if the grim reaper knocks without warning, obviously to our other halves everything is always £25, £50 or a £100 etc when it was probably treble or more.