Agree on the liner.

I only rarely wash down sleeping bags.  A USA specific camping store chain used to sell their own brand of soap for washing down stuff, when they discontinued the soap and put it on a clearance price, I bought a lifetime supply.  There are other brands of soap that is recommended for washing down.

I use a top loading washing machine, that is all I have.  But I think that front loading machines are suggested for washing down.  I will put the item (sleeping bag or winter parka) in the machine and try to compress it by hand as much as I can when I run the water (cold) into the machine so that bag does not all float to the top.  I then (after filling) try to squeeze as much air out of the bag as I can so the bag is not just floating on top.

Wash on delicate. 

Sometimes I have done a double rinse, you do not want to have soap residue in the down, that can prevent the down from fully fluffing up.

After rinse and spin, I will do a high speed spin to try to get as much water out of the bag as I can.

Only then when there is very little water left in it, I will lift the bag out.  If there is too much water in the bag, lifting it can tear out internal baffles.

I put it on a rack and use a fan to blow air at it.  Once it is dried out, then I put it in a clothes dryer on air only (no heat), plus a few tennis balls or maybe a tennis shoe to try to agitate the down and break up any clumps in it.  That is noisy, but a rubber sole tennis shoe won't break anything.

Optional, there are some down enhancements for sale these days that are supposed to make your down more water resistant, that is applied after washing but before drying.

I was pretty sure I kept a record of which sleeping bags I had washed and when, but I do not find it on my hard drive so perhaps I don't have records?

I would never wash a down bag. No matter what precautions you take, they inevitably come out with less loft. I always use a sleeping liner to avoid bags themselves getting very dirty, and when they eventually seem dirty nevertheless, I just purchase a new bag. You might want to look at the quilts from Cumulus, they are affordable and a nice design that packs up into less space than the full bags of old.

Sherpa rebuild almost complete: just needs racks, mudguards and lights. Anyone interested on here?

Will post list of components: new rear wheel, v-brakes, chain, rear cassette, front derailleur, stem, bar tape, cables, chain (plus Wipperman link) and seat post.

...probably intellectually too 

Here's one from SJS's website. Perhaps a benchmark. Have a look on ebay too.
Best wishes for a good sale.
https://www.sjscycles.co.uk/bikes/thorn-raven-discovery-with-spluss-couplers-and-rohloff-hub-ll-gunmetal-new/?geoc=JP