Well, the train was on time. I even got around the supermarket in good time, loaded the car and installed the aerial and radio by the time the pass was due to start. Because I really was mobile, I set the VFOs to the centre frequencies of the pass, rather than worrying about doppler shift.
Around 8 or 9 minutes into the pass, I started to hear signals from the AO-51 satellite. Signals built to a genuine S7 or 8 - with fading caused by the tumbling of the satellite as it travels through space. EA5ALH was heard with a good signal working Italian and other stations.
Because I didn't have the option to adjust the VFO on either transmit or receive, I was hearing the satellite for 3 or 4 minutes at a maximum, but it makes me think that a QSO will certainly be possible with a little preparation.