Hi again Ian,
must admit when I read this interesting query I immediately started thing about the many SUdburys around the country, having completely forgotten about your SEdbury near Tidenham/Chepstow. My grey matter is really not in good form tonite !

I must say your Sedbury is just outside my area of knowledge & experience, sorry. Again I strongly recommend you try asking messrs Pope & Parkinson.
However my gut reaction, based on a few hours searching the net including your links, is that the token is not related to Sedbury nr Chepstow.

However I do know of a grand stately house called Sedbury Hall near Richmond, North Yorkshire. This house is very famous for the breeding of throughbreds since the early days of horse-racing.
http://www.britishlistedbuildings.co.uk/en-323356-stable-block-approximately-one-hundred-m

Another site states
"On Tuesday, 29 May 1660 Charles II was restored to the throne. A week later his attention turned to horse racing and he drew up a deed appointing James D'Arcy (the elder) of Sedbury, as master of the Royal Stud. James D'Arcy was the sixth son of the 4th Lord Conyers of Hornby, near Bedale, who had suffered during the Commonwealth for his Royalist sympathies. The D'Arcy-Conyers family is complex, with dynastic links throughout Yorkshire. Sir Thomas D'Arcy, father of Arthur D'Arcy who wrote to Thomas Cromwell, Henry VIIIth's chief administrator, suggesting Jervaulx Abbey as a royal stud, was executed for his role in the Pilgrimage of Grace in 1537, but subsequent D'Arcys overcame this disaster by a series of advantageous local marriages, which maintained their social position. James married Isabel Wyvill (of Constable Burton Hall) and received the Sedbury estate as part of the marriage settlement. Their daughter Elizabeth (d.1720) married Ralph Milbanke (1689-1748) of Halnaby and a granddaughter Elizabeth (1706-1739) married John Hutton (1691�1768) of Marske. The marital links were mirrored in the interconnection of their horses, which assumes importance because of the unique nature of their stock [See D'Arcy family tree].

James D'Arcy was immediately commissioned to visit and report on the Tutbury Royal Stud in Staffordshire. James quickly informed Charles that the stud had been dispersed and could not be restored. However, he offered to supply him with "twelve extraordinary good Colts" for the considerable sum of eight hundred pounds a year from his own estate at Sedbury. Charles accepted, but the D'Arcy family was not always paid. His son James (the younger) (1650-1731), later Lord D'Arcy of Navan, spent much of his life failing to persuade subsequent monarchs pay Charles' debt. In effect Sedbury became the Royal Racing Stud and was the stable of the so-called "Royal Mares."
From, with a picture of Sedbury House) http://www.tbheritage.com/Breeders/FoundBreeders/NorthYorkshire/NYorksTeesWilk.html

Also see http://yorkshire-racing.co.uk/hist_pre_1800.htm
I hadn't realised the likes of Doncaster racecourse were 400 years old, not to mention Catterick which is even nearer to Sedbury.

So the name SEDBURY was associated with VERY influential and wealthy people indeed upto the early 1800s, so just before the ironworks token was minted in 1813.

NOW I must stress I've read nowt tonight to show any clear link between the dirty world of ironworking and the grand rural bliss of Sedbury House/Hall & Stables.
http://www.genuki.org.uk/big/eng/YKS/NRY/Gillingwest/Gillingwest68.html

However it's not far at all from Sedbury to the coalmining and industrial areas of Darlington & Durham which saw great expansion & investment at about the same time as the Sedbury stables c late 1700s. I wonder if some of the D'Arcy family money gained from their horse breeding and racing was invested in the up & coming industries a few miles away in Darlington, one end of the world's first steam railway opened in 1825 to carry coal to the port of Stockton on Tees ?. The fact that, as you say, the Sedbury coin token carries the same design as the wellknown Phoenix Iron works of Sheffield, also Yorkshire, perhaps adds credence to this ?

All supposition of course, but not impossible methinks.
But more important, what do you or anyone else think ?

Please be assured I'd love to think that this was all just wishful thinking, and in fact there was once an ironworks at Sedbury FoD c1810, but the lack of clear evidence makes me doubtful.

Yes! The earlier bridge looked something like this on one side and with stone piers on the other. (I couldn't find a full picture online quickly but have one here!)

http://www.caerleon.net/history/ggat/bridge/pictures.htm

The bridges crossing the Wye, give or take a bit on this site have a very long and interesting history. I was trying to work out if the commonly written history on all the modern web sites was actually correct or just something someone had written as an idea or memory at some point which has just been copied and possibly embellished over time. Great thanks for the help.