Thanks for the quick reply!
Alas I'm now getting errors on the read line below. So I've now got code like
open(20,file='mobcal.run', status='old')
read(20,'(a30)') a10A1
read(20,'(a30)')
read(20,*) i2
close (20)
and an error like this in g77:
fmt: end of file...