Thanks for the info.
Now that I have one of the keys on my keyring and have put the other on the spare keys ring I'll have another go at it.
I'm sure my neighbors were happy (as I was) to know the car has an alarm...

__________________
95 E300D working out the kinks
77 300D, 227k, station car
83 300CD 370k, gone away
89 190E 2.6- 335k, no more
79 VW FI Bus- 145k miles, summer driver
59 VW Beetle ragtop- 175k miles
12 VW Jetta- 160k miles