In message
-sept
ember.org, at 22:18:44 on Wed, 27 Apr 2016, Recliner
remarked:
Mr. William Rodgers - My Department contributed 25 per cent. of the
total expenditure of £18.5 million incurred up to 31st March 1975.
Expenditure since then, estimated at £7.2 million to 31st December
1976, qualifies under the Local Government Act 1974 for transport
supplementary grant at the rate of 70 per cent. The total cost of the
work outstanding at 31st December 1976 is estimated to be £3.6 million.

http://hansard.millbanksystems.com/w...761215_CWA_194

So the total cost was approx 18.5 + 7.2 + 3.6 = 29.3 million.

Using RPI, that would be around £220 million in todays money.

Of course that was for the original two-station extension, but it
nevertheless seems very low (and presumably doesn't include anything for
the several additional trains needed for the extension, but presumably
ordered in anticipation).

Tube lines have fleets of identical trains, you can't just order a few
more later.

What was the total cost including the two separate, subsequent extensions
for T4 and T5, the latter also requiring a new grade-separated underground
junction for the T4 and T5 lines to the west of the T123 station? Those
extensions would certainly have much more than doubled the total cost.

And generate double the fares.
--
Roland Perry