Dear Graeme;
I have written a VisualLISP program to change existing
text objects to incremental numbers.
Just copy and paste the below expressions into a text file
and save it with NN.LSP file name. Then load it into AutoCAD
using the APPLOAD command.
Enter the command "NN", enter the starting number and
at last successively select existing text objects to
change them to incremental numbers.
(defun c:nn( / e elist n )
(if (not (numberp *nncounter*))
(progn
(initget 1)
(setq *nncounter* (getint "\n Start from : "

)
)
(progn
(princ "\n Start from <"

(princ (rtos *nncounter* 2 0))
(princ "> : "

(setq n (getint))
(if (numberp n)
(setq *nncounter* n)
)
)
)
(while (setq e (entsel))
(command "._UNDO" "G"

(setq elist (entget (car e)))
(setq elist
(subst (cons 1 (itoa *nncounter*))
(assoc 1 elist) elist)
)
(entmod elist)
(command "._UNDO" "E"

(setq *nncounter* (1+ *nncounter*))
)
(princ)
)
Regards,
Farzad