Got the portafilter back today.
Unfortunately, I took only two photos prior to plating:
In the second image, you can somewhat see the extent to which the original plating had worn off. Bare brass was visible inside the holder, and the ears were well worn of their finish, too.
Newly nickel-plated:
It turned out pretty much as I expected. This was less of a vanity procedure than one to save the original portafilter. A new replacement holder will not fit the Club without significant finessing—the space for the ears in the group is much smaller than a Cremina. My bottomless PF works, but I need a working portafilter that I know will last for a long time.
To give you an idea of the difference between nickel plating and the original (chrome?) plating, see the difference between the spout and the holder:
The nickel finish is beautiful but not the same as original. No worries. I knew it would be different. Nickel is food safe, and that is the important thing.
In summary:
Plating: £70 (their minimum charge for any item)
Shipping: £10
VAT: £16
Total cost: £96
Time for completion: 2.5 months
Number of emails exchanged: 17
Would I use Ashford Chroming again? Probably not. They were nice, but you deal with one person in the shop, one who deals with finances, and ere the twain shall meet. It never seemed as if any one person knew what was happening, and the time it took for a simple reply was rather long. For example, it took three days between notification that I would get an invoice until I actually did get it, and then it took another three (four?) days after payment before the part was shipped back to me.
They did include a small packet of Gümmis, so I guess that makes everything better.