"Webb" is an occupational name, meaning "weaver". As such there probably were gypsies with the name - but there were even more non gypsies also with the name.
Following your logic, Roger, that gypsies tended to intermarry, which I have found to be largely true, then the Docwra, Hodge, Cross and Witherow names that the Webbs in this thread married must be gypsies also.
In my experience I think it's very improbable
"I think they were gypsies, you just haven't found the evidence" is not an argument that I buy!
David