John, yes the min temp pattern on Tuesday night was quite interesting in the SE. Shoreham is close to the River Adur and it can lie under the katabatic flow as it pushes through the gap in the South Downs immediately north of the airfield. The breeze must have dropped sufficiently low for the low-level flow to become detached from the flow aloft. A similar thing happened at Usk in Monmouthshire - by the river, classic frost hollow site on occasions.

Notable too that two other cold sites were Alice Holt Lodge (Farnham) and Santon Downham, Norfolk / Suffolk borders. Both are in sheltered clearings in woodland.

Julian
Molesey