Renfrewshire, in common with other Scottish counties, has long had a flag of its own (covered previously), a banner of its coat of arms. The enduring problem remains that these are registered armorial bearings, protected by law and property of the individual or body corporate to which they are granted. This is enforced in Scotland by the delightfully feudal Lyon Court, given wide powers by 17th century legislation to curb misuse.
In England particularly, new county flags - that can be flown by anyone - have taken off and gained widespread acceptance. Some are historic - the flag of Cornwall has been in use since the 19th century - but most are recent, drawing on traditional designs and motifs. The flag of neighbouring Devon, adopted by the county council in 2006, has been particularly successful.