The new Colonel of the Regiment, Major General Colin Shortis, applied his very considerable energies to building on the platform provided by his predecessors and, in the process, greatly strengthened the Regimental structure. In 1986 the Charter of the Regimental Committee was altered and the following year there was a major development: a new Home Defence TA Battalion was to be formed. The project officer, Major Pape, was in place at Butts Road TA Centre, Exeter, by February 1987. Lieutenant Colonel Robert Steptoe, the first Commanding Officer, took up his appointment that October. The new battalion, 4th Battalion, The Devonshire and Dorset Regiment (4 D and D) comprised Battalion HQ and E Company at Exeter, A Company at Plymouth while B Company was split between Paignton and Torbay. In the first instance all the representation was from Devon. In October 1990 this imbalance was addressed when C Company at Dorchester joined from 1 Wessex, thereby creating a footprint in both counties. On 19 March 1988 there was a landmark occasion as the Regiment was granted the Freedom of Plymouth, not only the largest city in either county, but also the Regiment's most fertile recruiting ground. This parade was the first ceremonial commitment for the 4th Battalion while the 1st Battalion, which was now in Bulford, was also well represented. The previous year the three Regimental Associations, having carefully preserved their separate identities for almost thirty years, agreed that the time had come to form a single Regimental Association. On 14 May 1988 there was a Vesting Day Parade at Bulford during which, symbolically, all three Associations marched on parade separately, before marching off together. The Colonel-in-Chief was present on this historic day, together with over 3,500 members of the Regimental family. The following May the 4th Battalion hosted the first of the now familiar annual Regimental Days, combining a parade, a Service of Remembrance, the Colonel of the Regiment's Reception and a reunion, bringing together all elements of the Regimental family.
In 1985 both C and E Companies of 1 Wessex camped at Sennybridge in September. C Company (Major Cook) made a considerable name for themselves on the shooting range. In 1986 both companies went to Denmark on Ex Bold Guard, since they were very much part of the UKMF. E Company joined the newly-raised 4th Battalion in 1987 while C Company joined 1 Wessex for camp that year at Sennybridge and, the following year, were back in Denmark again. In 1988 the 4th Battalion went to Okehampton for its first annual camp, which was followed that September by Ex Drake's Drum, South-West District's Home Defence exercise. Less than a year into its existence the 4th Battalion already had an excellent reputation although recruiting remained a priority. The Battalion held its Skill-at-Arms Meeting in April, before taking on the responsibility of running South West District's concentration of Home Service Force (HSF) Companies at Sennybridge. The Battalion was raising G (HSF) Company at Plymouth at this time. The highlight of the 1989 was Ex Summer Sphinx, a battalion exercise involving FIBUA and heliborne deployment on Salisbury Plain.
Lieutenant Colonel Charles Cooper assumed command in April 1990 and, when C Company from Dorchester joined on 8 December that year, the 4th Battalion proudly took its place in the Army's order of battle.
From 1985 Lichfield was the Regimental Depot for the training of adult soldiers but Crickhowell closed in 1987 and the training of junior soldiers was centralised at the Junior Infantry Battalion at Shorncliffe. Eventually Lichfield's responsibilities for the training of adults expanded to include TA recruits, potential NCOs and potential officer courses. From the Regimental point of view the real disappointment was that training took place so far from the West Country. As with much of the Army during the late 1980s, the future of Regimental Museums and RHQs had been subjected to considerable scrutiny. In fact it wasn't just these important symbols of Regimental identity that were under threat, it was the very existence of The Devonshire and Dorset Regiment itself. In June 1990 Lieutenant General John Wilsey succeeded Major General Shortis as Colonel of the Regiment. The same year Major Pape succeeded Colonel Tremlett as Regimental Secretary and Lieutenant Colonel Roberts succeeded Lieutenant ColonelBurdick as Assistant Regimental Secretary.