Besides its relationship to the six principal geographical features, Tinkinswood is also exactly 2,000 poles from the mouths of the river Thaw and the river Taff. The Taff estuary is wide, but the spot at map reference ST 193725 is 2,000 poles from Tinkinswood and also 3,000 poles from the burial sites near Creigiau and at Cleppa Park, Newport, referred to in the unit on Common Features of Burial Sites in the Vale of Glamorgan. So, as we saw with Usk Mouth and the end of the ‘Rivers’ line, (see the unit on the ‘Rivers’ line) we can tie down even a general area such as a river mouth to a precise spot by seeking its relationship to other sites.

2,500 poles to the north east of Tinkinswood - the same distance as to the end of the ‘Mountain’ line on Foel near Llantwit Fardre - is another well marked summit - Craig yr Allt – standing 274 metres above sea level. This can be found above Taffs Well on Caerphilly Mountain. So here we have two summits equidistant from Tinkinswood. And just as the direction of the Llantwit Fardre Mountain was marked by the site of the church at St Nicholas, so the direction of the Craig y Allt summit is marked by the church near the village of St Georges. There is a high probability that these churches were built on former ancient sites.

Tinkinswood is also related to a third summit. This is Garth Hill – a prominent landmark (307 metres) to the north-west of Cardiff on which is built a ‘Tumulus.’ The imaginary line joining Tinkinswood to this summit lies at an exact right angle to the ‘Coastal’ line (Hutchwns Point to Penarth Head). Again the direction of this imaginary line is marked by a church – this time the one in the village of St Brides super Ely. (See Figure 4 below).