He should stay with his existing insurer if at all possible and just pay the renewal.
My late father had the same problem, over 80 with a MX5.
No one would even quote him so he stayed with LV (excellent), just paid the renewal and said nothing.

1969 4/4
1995 plus 8
1996 Plus 4 4seater
2002 Aero S1
2013 M3W
2014 Plus 8