In search of some winter sunshine to warm my bones I walked through undulating Hertfordshire countryside to the Pegsdon Hills which straddle the border with Bedfordshire and offer sweeping views into the flatlands of East Anglia. This diary takes only a passing interest in geography but these hills are notable for several reasons.
 They form the start (or the finish) of the Chilterns, the chalk escarpment that bulges across southern and eastern England. The Icknield Way passes through here- part of the ancient ridgeway route that runs between the Dorset and Norfolk coasts.
 I was on a particular mission to reach the Trig Point shown above, being the highest point roundabouts. Trig Points were built across the country at such locations by the Ordinance Survey from 1935 onward as part of the retriangulation of Great Britain. On this walk for example I was guided by OS Explorer Map 193 1:25 000 scale.
 One other geographical reason for choosing today's walk: this range of hills is a section of the watershed between the London Basin and the Wash. In our kingdom of rains the precipitation drains along this margin either towards London or towards the north-west corner of Norfolk on the east coast of England. This Trig Point must be one such spot where the water goes one way or the other.
 I'll return in summer because the Pegsdon Hills are also noted for their wildflowers, including some rare ones particular to chalk grasslands which are now a scarce habitat.