Following Trevor's report of his record May frost in eastern Scotland last night, with the recent slackening of the nagging (as they say) NE wind, attention turns to the possible plight of my dahlias.
The MeteoGroup MOS (model output statistics) min temp forecast for Wisley, Surrey is - 0 C (i.e. just below 0.0C). Wisley is cold when the ground is dry. Heathrow is +3 and many rural areas in S England are showing as +1C, implying a widespread ground frost. It was too windy earlier on for me to cover the small plants (I keep them in the ground each winter and they have only come up in the last few weeks). I can't remember a late frost here in recent years but I'm sure many here will know how sensitive they are (dahlias, not the group members) to the first decent frost of autumn. I'm assuming that the warmth of the patio will help the sweet peas through - waiting to be planted out.