"Knght of the Golden Fleece" is unusual portrait of Charles I

Horta, from Belgium, sells on 9 October 2017 a "Flemish School, 17th century" "Portrait of a Knight of the Order of the Golden Fleece", estimated at 2500 to 3500 Euro.

It is a portrait of King Charles I of England, probably based on a portrait by Anthony Van Dyck.

The inscription reads "Away I pass / from what I was", probably a reference to his death, but a line I can't find any reference or source for. Mourning portraits for Charles I are not unusual, but are often in miniature or otherwise easily hidden, as royalist sentiment wasn't really a healthy sentiment at the time. The larger scale of this one may indicate a later origin, or that it was kept abroad (e.g. by some family which had fled England for the Continent). Paintings of Charles I with his crown seem to be rare, and only add to the post-mortem royalist flair of course.

Artistically, the painting isn't too bad but would struggle nevertheless to reach the bottom estimate. But with the correct subject and the potential history behind it, this one might fetch a lot more if it is noticed by the right collectors.

UPDATE: the crown worn by Charles I here is the St. Edward crown, not the earlier crown which was dismantled after the execution of Charles I. Since this new crown was created in 1661, the painting is not older than that, or the crown has been added to the painting at a later date of course.

UPDATE 2: not sold probably, again for sale at Horta on 22 January 2018 with a better description (portrait of Charles I) and an unchanged estimate of 2500 to 3500 Euro.

UPDATE 3: sold at Sotheby's (!) in September 2018 (in an online only auction) for  £3,500, not bad at all.