Ok so I managed to get the agent started. The reason for the above error was the Java classpath.
After I set the classpath the LoadUI agent on the Ubuntu box starts up however I now get the following
javax.net.ssl.SSLHandshakeException: Received fatal alert: certificate_unknown
at sun.security.ssl.Alerts.getSSLException(Unknown Source)
at sun.security.ssl.Alerts.getSSLException(Unknown Source)
at sun.security.ssl.SSLSocketImpl.recvAlert(Unknown Source)
at sun.security.ssl.SSLSocketImpl.readRecord(Unknown Source)
at sun.security.ssl.SSLSocketImpl.performInitialHandshake(Unknown Source)
at sun.security.ssl.SSLSocketImpl.writeRecord(Unknown Source)
at sun.security.ssl.AppOutputStream.write(Unknown Source)
at java.io.ObjectOutputStream$BlockDataOutputStream.drain(Unknown Source)
at java.io.ObjectOutputStream$BlockDataOutputStream.setBlockDataMode(Unknown Source)
at java.io.ObjectOutputStream.<init>(Unknown Source)
at com.eviware.loadui.impl.messaging.socket.ServerSocketMessageEndpoint.init(ServerSocketMessageEndpoint.java:69)
at com.eviware.loadui.impl.messaging.socket.ServerSocketMessageEndpoint.newInstance(ServerSocketMessageEndpoint.java:42)
at com.eviware.loadui.impl.messaging.socket.SocketServerEndpoint$ConnectionAccepter.run(SocketServerEndpoint.java:131)
at java.lang.Thread.run(Unknown Source)
14:25:32,296 ERROR [ServerSocketMessageEndpoint] Connection closed: