I am not sure about Thomas but we know this Henry is not related (directly at least) to Henry and Jane Sewell. He appears in Virginia about 1627 and immediately moves to become a landowner as well as a seat in the House of Burgesses in 1628. He was married to Alice Willoughby, sister and not daughter to Thomas Willoughby of Willoughby Spit.
Alice was not Thomas' daughter but sister; alas, my brother and I went to their howe, Bore Place in Kent, last September and the family records they maintain of the owners of the land show only male members of the Willoughby clan, not females. The estate was sold about 1615 to other parties (the Willoughby family was centered at Wollaton Hall in Nottingham and sold the property for needed capital).
We checked with the rector of the parish church in Chiddingstone and unfortunately it had been hit by lightning in 1634 and internally burned up,thus taking all records with it.
One of the descendants of Henry and Jane Sewell DID come to Virginia, but much later and was secretary to the royal governor. Our Henry was a Puritan and therefore his descendants moved to the Severn River in Maryland after the Civil War in England.