The Modern Railways report on the Exeter re-signalling scheme quotes an overall reduction in points from the old 'mechanical' layouts of 557 to 294 on the panel; i.e. less than halving even over the extremes of scheme progression. I can find no reference to any mid-scheme de-scoping. The new layout at Taunton is described as having greater capacity (thanks to closer signal spacing) and higher speeds.
Modern Railways' reports on the overall West of England Resignalling (Westbury and Exeter) cover its 'launch' in 1976.
The special Railway World special issue on the re-signalling (by well-respected author, Adrian Vaughan) records stagework as having started in September 1978. This book speaks very positively about the new layout at Taunton with no mention that I can find about de-scoping.
The general election that brought a change of government was not until 1979.
I have absolutely no doubt that the later stages were de-scoped from initial proposals. I was told this explicitly, and shown the diagrams, by the signalling engineers who were designing the scheme. I don't have a copy of the Railway World Special. I suspect the descoping took place very much behind closed doors before any information was released into the public domain and certainly well before any signalling notices were published to operations staff. To be fair to the administration of the time the layouts actually built probably suited this period characterised by the lowest passenger traffic figures ever experienced on the British rail network (possibly until 2020!). The track and signalling layout designs, while very 'lean', were highly optimised, and speeds of turnouts etc were improved markedly for many frequently made moves. I don't criticise the engineers. They did their very best within the scope of what they were allowed to spend. Some of the decisions made have definitely hampered service growth, flexibility and reliability since however. At Taunton, operators were very lucky in being able to reactivate the centre island platform economically later without the costs of any additional signalling or track layout work, but another big disadvantage of the layout as it stands is anything going in or out of Fairwater yard at the London end must go through the down platform loop. That was a more serious constraint before the centre island was reopened - it wasn't so busy then as it has been more recently as a major track renewals base though. In the initial proposal I believe there was to to be a ladder of additional left hand crossovers at the west end of the station that did not survive the review.
Here is a chronology of the West of England Resignalling and related schemes, from defunct Signalling Notices website, my training notes and other sources:
Signalling Notice No. - Date – Scheme – Stage – Site and details
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? - October 1978 - Westbury South area resignalling. The signalling was controlled from a small panel in Westbury North SB. Fairwood Junction also resignalled but still controlled from the local SB
? - 1979 - Warminster area added to Westbury North panel
No.1 - April 1984 - Westbury Resignalling - Stage 1 - Westbury Area (Panel Opens) - Westbury North, Fairwood Junction, Haywood Road Junction and Hawkeridge were closed
No.2 - October 1984 - Westbury Resignalling - Stage 2 - Frome Area
No.3 - Exeter Resignalling - Stage 1 (Preliminary Works) - Exeter Central
No.4 - November 1984 - Westbury Resignalling - Stage 3 - Witham Area
No.5 - December 1984 - Exeter Resignalling - Stage 1 (Preliminary Works) - Cowley Bridge Junction to Crediton singling and conversion to key token
No.6 - February 1985 - Westbury Resignalling - Stage 4 - Castle Cary / Somerton Area
No.9 - March 1985 - Exeter Resignalling - Stage 1A – (Panel Opens) Exeter St. David's / Crediton / Stoke Cannon
No.10 - Friday 3rd May - Monday 6th May 1985 - Exeter Resignalling - Stage 1B Exeter St. David's / Exeter City Basin / Exmouth Junction
No.11 - Saturday 7th December - Monday 9th December 1985 - Exeter Resignalling - Stage 2 Stoke Cannon (inclusive) to Tiverton Junction (exclusive)
No.12 - March 1986 Exeter Resignalling - Stage 3 - Tiverton Junction (inclusive) to Silk Mill (exclusive)
No.13 - April 1986 - Exeter Resignalling - Stage 4A - Bridgewater (exclusive) / Athelney (inclusive) to Taunton East Junction (exclusive)
No.14 - Friday 9th May - Monday 12th May 1986 Exeter Resignalling - Stage 4B - Cogload Junction (exclusive) to Wellington (exclusive)
No.24 - Friday 14th November - Monday 17th November 1986 - Exeter Resignalling - Stage 5 - City Basin (inclusive) to Newton Abbot (exclusive)
No.25 - Friday 1st May - Monday 4th May 1987 - Exeter Resignalling - Stage 6 - Newton Abbot East (inclusive) to Paignton North (exclusive) and Totnes (exclusive)
No.25A - Friday 1st May - Monday 4th May 1987 - Exeter Resignalling - Stage 6 - Newton Abbot East (inclusive) to Paignton North (exclusive) and Totnes (exclusive) (Amends Notice No 25)
No.27 - October 1987 - Exeter Resignalling - Stage 7 Dainton Tunnel (exclusive) to Totnes (inclusive)
No.28 - October 1987 - Between Crediton and Barnstaple, NSTR loop I think
No.31 - February 1988 - Special signalling facilities between Dawlish Warren and Teignmouth (issued retrospectively) – A method based on ‘Absolute Block’ for use through a ‘long section’ during widespread failures of track circuits on the sea wall. Instituted by panel supervisor only by means of a special panel key switch. Procedures for train arrived complete confirmation. Removed when TCs replaced by axle counters
No.40 - March 1990 - Westbury - Bradford Junctions Area
? - ? - Paignton North SB Closure – Transfer to Paignton South SB
? - ? - Paignton South Closure – Transfer to new Paignton panel in station office
? - ? - Axle Counters – Various schemes to convert train detection on sea wall and Exe estuary