According to Wikipedia Shad Thames is named after St Johns at Thames Church, but across the river: Shadwell - Wikipedia, the free encyclopedia: EtymologyIn the 13th century, the area was known as Scadflet and Shatfliet[1] – derived from the Anglo-Saxon fleot, meaning a shallow creek or bay – the land was a low lying marsh.[2] A spring, issuing from near the south wall of the churchyard was dedicated to St Chad, and filled a nearby well.[3] The origin of the name is therefore confused, being associated with both the earlier use and the later well. Shadwell was formerly called Chadwelle.[4] I think it much more likely that they both derive from a similar source, and shallow creek does fit.