[1] The sandy soil of the hill-top is more attractive to burrowing animals like badgers, than the heavy London clay of the surrounding areas.

The A5 trunk road runs across the summit of Brockley Hill using the same alignment of the highway (also known as Watling Street) built by the Romans in the 1st century AD.

A smaller Roman road is supposed to have branched off from the top of Brockley Hill in the direction of Watford, King's Langley, Berkhampstead, and Tring, however, there is no evidence of this route according to studies of the parish boundaries.

Although both sections of Roman road approaching Brockley Hill are straight, a direct course across the summit was abandoned in favour of a double-bend alignment.

What now lies between Brockley Hill and Pennywell includes eight lanes of fast moving traffic, as both the M1 motorway and the A41 Watford Bypass pass through this area.

The Eastern end of the Dark Ages linear earthwork known as Grim's Ditch or Grimsdyke is close to Brockley Hill.

The Mary Wardell Convalescent Home was founded on the summit in 1882 and the premises were bought to be the Country Branch of the Royal National Orthopaedic Hospital in 1920.