Hi Mike,
Well ... it all depends ... here in the USA, that is. I designed the auction program in our office, which I named the Sealed Bid Sale. During good market conditions, houses can sell for over asking price. In order to create a bidding war, you can use an "auction" atmosphere ... people are initially getting a good deal at the opening bid, but that deal can erode as competing buyers decide to bid.
In a Sealed Bid Sale, used more often in commercial real estate (which is what I do) the seller sets a "reserve" wherein they do not have to accept a bid lower than a certain amount. So, for example the Society could have an opening bid of £170,000, with a "reserve" of say £200,000. They, then can refuse to even look at a bid under £170,000, and reject any bid under £200,000 ... but must accept any bid over £200,000.
In California, especially the Bay Area around San Francisco, it is not uncommon during excellent market conditions, to see homes sell for $20,000 to $40,000 over asking price ... and that happens without any auction. We have had that happen here some in the Chicago area. Given I was originally from California we decided to try auctions here ...
So, the Society could be trying to do one of two things ... sell off quickly to get cash before property taxes are due (assuming the UK taxes property) and avoid other holding costs ... and/or realize a greater profit by creating a bidding war.
If they had any gumption, they would listed it with a JW Realtor, and let him/her make some money. They should also do as you suggest, and share the funds with the local JWs, or with the more needy ... you know, some good old fashioned charity ... after all, the Society worked very hard to be registered as a charity in the UK ... over and above objections coming from ex-JWs across the pond.