First borne by Edmund Del Clay in 1399
Many people state, not just Clays, that this whatever, whatever is our family coat of arms, it isn't.
Coats of Arms are granted to one person, they may be inherited, complete as granted by their heirs and as time goes on they are halved, quartered etc, etc.
They should only be borne by those people who were the original grantees or their heirs.
Henry VIII, instituted what became known as visitations, these visitations, comprised of Heralds, they visited the counties of England to clarify that those people using or claiming coats of arms had the right to bear them. In two instances, two members of the Clay family were denied the use of arms after a visitation.
Here is a quote from the College of Arms
"there is no such thing as a 'coat of arms for a surname'. Coats of arms are inherited in the male line and so are surnames. But a coat of arms is granted or confirmed to one person and their descendants in the legitimate male line so only that family group will be entitled to the coat of arms, not everybody of that surname. As such many people of the same surname will often be entitled to completely different coats of arms, and many others of that surname will be entitled to no coat of arms at all. For any person to have a right to a coat of arms they must either have had it granted to them or be descended in the legitimate male line from a person to whom arms were granted or confirmed in the past."
Please visit their website
https://www.college-of-arms.gov.uk/resources/faqs
The short answer to this is no.
There is a court that deals with the law with regard to this, The Court of Chivalry, however it hasn't sat since 1954 and prior to that since 1737.
In 1954, The Lord Chief Justice, confirmed that the Court retained both its existence and its powers. However after the case in 1954, the Lord chief justice had this to say, "if this court is to sit again it should be convened only where there is some really substantial reason for the exercise of its jurisdiction."
So, although the Law of Arms remains part of the law of England and although the Court of Chivalry exists, there is difficulty in enforcing the law in practice. The illegal use of arms in English law does not mean that there are no rights infringed, merely that it is not within the jurisdiction of the common law courts to act and that the court that does have the power to enforce the law, no longer sits.
So you can use the coat of arms, without fear of being dragged through an archaic medieval court, however you should not use the coat of Arms for business or financial gain, just keep it personal. It would be so much better if people used the coat of arms, to display their connection with the worldwide Clay family, than use the name of a non existent coal baron.
Many people claim to be descended from the son of Sir John Clay who was knighted at Tewkesbury and then present the above coat of arms, this is incorrect, the coat of arms borne by Sir John Clay, father and son is as below.
Father and son
The senior Sir John later had his arms quartered with that of his wife's family.