According to British History Online (Victoria County History) Montacute was of sufficient importance to have been visited by Henry III in 1250 and in 1340 the borough had the ninth highest tax in the county, but Montacute's significance declined in the 16th century.
Montacute is clearly marked on Christopher Saxton's 1579 map of Somerset (below); St Michael's Hill is indicated as 'ye tor'. Note the old name for Yeovil, 'Evill' -
And again Montacute and the hill is indicated on John Speede's 1611 map as 'the thor' (see below):
These maps were drawn up after the dissolution of the Montacute Priory in 1539. We know from Leland that in 1542 Montacute Priory Chapel stood on the mound of the old Norman motte and bailey castle on St Michael's Hill, but we also know from Thomas Gerard of Trent that in 1633 the Chapel was in ruins. So the etymology of 'tor or 'thor' labelled on the above maps could derive from the Old English 'watchtower' and/or the Middle English 'rocky hill'. The present-day tower on the hill was not built until 1760.
The antiquarium William Stukeley (1687–1765) drew many archeological sites including the view below (dated 1723) of Montacute Hill, Hedgecock Hill and Ham Hill as seen from the Fosse way. It is intriguing that no dwellings or churches are depicted:
The earliest map I can find showing roads through Montacute is the 1782 Phelips map of the Manor of Montacute. This map, held by the National Trust, seems to be a redrawn version of a map by Samuel Donne that was held in the Somerset Record Office, but sadly was lost. The Country Life Magazine archives still have a photograph of this original map. On this map the road east of the house appears as minor track while the major road through the village runs west of the house. This road was adopted by the Ilminster Turnpike Trust in 1781. Possibly influenced by this, in 1786 the fifth Edward Phelips created an new entrance on the west side of the house using the porch from Clifton Maybank house.
The next map I found is from the Georgian and Victorian Ordnance Series Old Series published on Archi UK; although first published in 1805 it still clearly shows the original road passing east of Montacute House. This map was drawn up before the main road was altered with the creation of the current west drive.
An 1825 map of Montacute Parish and an 1840's tithe map also both show the road through Montacute in its original form, without the new tree-lined west drive but with the previous (north-west) drive. The picture below was painted in 1825 by James Johnson; the church tower is visible behind the house on the right of the picture but on St Michael's Hill the tower is not shown:
The image below is the 1840's tithe map accessed on the map database 'Kypwest':
The 1840 map above shows the road running past the east of the house as a minor road, and a major road running past the west of the house. It clearly shows the north-west drive that was created when the front porch was built onto the house. This drive had a turning circle in front of the west aspect of the house and joined the old Tintinhull Road junction which was subsequently diverted. In the picture below I show the approximate route of the present-day roads overlaid on the map. The main road through the village is indicated with red dots, the new Montacute House West Drive in yellow, and Back Lane in purple. The old road junction for Tintinhull (between plots 111-115 and 201 on the tithe map) was incorporated into land that now includes the orchards of Montacute House.
The 1844-1888 OS series map of Montacute (again from the fantastic Kypwest website) shows the altered route of the main road through the village and the new Tintinhull turning; I have indicated the previous location of the roads and the Tintinhull Junction in red:
