passing [Rosie- The outer one is, I understand, somewhere around Redhill - and tomorrow I will be too so I'll keep an eye out!]

for (Snodders) If the outer one is around Redhill, the inner one must be somewhere near Croydon, say. These places are perilously close to where I live (Warlingham). "Passing showers" to use rather dated meteorological terminology. :-(