I'm aware of the Velthouse near Longhope Brook, heading south from Longhope towards Blaisdon :-

The Velthouse, an outlying farmstead to the north, was recorded from 1591; (fn. 27) it was rebuilt in brick in the 19th century.

From: 'Blaisdon: Introduction', A History of the County of Gloucester: Volume 10: Westbury and Whitstone Hundreds (1972), pp. 6-7. URL: http://www.british-history.ac.uk/report.aspx?compid=15734 Date accessed: 02 August 2009.

What context does Vailbrook appear ?