The phrase "a longstanding agent" is correct and usable in written English.
It can be used to describe someone who has been an agent for a long period of time, often implying experience or established presence in a particular field.
Example: "The company decided to renew the contract with a longstanding agent who has consistently delivered excellent results."
Alternatives: "an established agent" or "a veteran agent".
Bleakely prompted speculation that she would end up at ITV after she sacked her longstanding agent Noel by text earlier this month, reportedly saying: "It is better if we go our separate ways.
Though Mr. Ford is blessed with impressive contacts in Hollywood -- the famous actresses he has dressed, a longstanding friendship with the agent Bryan Lourd, a partner at the Creative Artists Agency -- these relationships, some producers and development executives said, would not guarantee him a career in directing.
"Our investigation found that memento taking at recovery sites has been a longstanding practice with F.B.I. agents," the inspector general's report found.
Her manager, Shelley Browning, who has a longstanding relationship with Rapace's Swedish agent and represents a number of foreign citizens working in Hollywood, helped facilitate that change.
Campaigners against Russia's increasingly severe crackdown on gay rights will be cheering a small victory, after a court in St Petersburg overturned a verdict on appeal which had condemned a longstanding LGBT film festival as a "foreign agent".
Into this fraught atmosphere, the emotive issue of racism on the catwalk is being brought into focus by Bethann Hardison, a former model and agent who has waged a longstanding campaign for more diversity on the catwalk.
Michael German, a fellow at the Brennan Center for Justice and former FBI special agent, said: "This is clearly a longstanding problem where journalists, particularly journalists who are writing critically of US foreign policy, seem to be targeted in this way".
Carlos García, the director of Puente Arizona, a Phoenix-based grass-roots group that helped organize Wednesday night's protests, repeated a longstanding demand for the city to remove ICE agents from the jail at 4th Avenue.
Nobbs, who was best known as a comedy writer, was also a longstanding patron of the British Humanist Association, which, along with his agent, confirmed he had died.
There has been a notable or notorious debate about whether the agent's reasons in acting are causes of the action — a longstanding debate about the character of our common sense explanations of actions.
