Copy after a lost Rubens?

Chorley's, from England, sells on 28 January 2020 a "Flemish School, 17th/18th century" Achilles discovered among the daughters of Lycomedes, a very large canvas (150 by 228!) estimated at £2,000 to £3,000.

It is not painted terribly well (it looks more like a 19th century copy, though a good enough one to be worth buying), but the composition is pure Flemish Baroque quality, so that's where I started looking.

Sure enough, the Prado has a Rubens / Van Dyck collaboration with the same topic and many similar parts (e.g. the two daughters at the front), but it isn't the same in the end.

Looking further lead me to the Danish Statens Museum for Kunst, which has a Rubens drawing showing the composition of the work for sale. Well, the horizontal version that is, where all figures are placed together much closer, giving a more intense painting, and avoiding the empty vertical space right in the middle.

The RKD lists a copy after this work, offered by Hampel auctions in Germany in 2015 (I can't immediately find it there). This version was known as early as 1854 as by Van Dyck, and later as by Rubens, but is now considered a (very good) copy.

The Prado version is known through several copies (from Nicholas Ryckmans and Cornelis Visscher II), but the other version, which interests us here, also has been turned into an engraving, by Frans van den Wijngaerde: this engraving explicitly states that it is a work after Van Dyck. As it is made in the decades directly after Rubens and Van Dyck died, chances are that this attribution is correct. This version was found at the Rijksmuseum. The British Museum states that despite the engraving being made between 1630 and 1645, they are still wrong with the Van Dyck attribution and it is a Rubens anyway.

The version for sale is the only one I can find with the horizontal format. Whether this is an invention by the copiist, or some lost or online not available version exists with this less successful format is unclear to me. It is in any case an interesting work if you are interested in Rubens or Van Dyck.

UPDATE: sold for £4,500, double the estimate.