Great Northern - Kings Cross/Finsbury Park to Letchworth via Welwyn and Hertford North. This went over to DOO in 1986 I think. Although this cab ride video claims to be from 1985 where it is discussed that training has started that week. Class 317s are mentioned - I didn't think they were on the GN as early as that, but maybe they were. Have a listen to some interesting views from 13m39s between Hadley Wood and Potters Bar where DOO is talked about!
Later the outer Suburban went DOO when new trains arrived to displace the class 312s that were previously used. Extensions of the overhead wires to Huntingdon, and onto Peterborough occurred just before this but went DOO soon after opening to electric trains as class 317s entered service.
There was an extension of the overhead wires to Cambridge as well later on. That would've been DOO as soon as that was done.
Going back to the inner suburban, the Northern City Line from Finsbury Park to Moorgate, which includes an underground section, was converted later and ran with guards into the 1990s.
Euston, mentioned above, did go DOO - but only the DC services to Watford Junction.
On Strathclyde, Guard's were sacked when they went on strike in protest, but things got political when Strathclyde, the Labour-run local authority (who subsidised the service) threatened to reduce subsidies and cut the service if they weren't reinstated. Eventually they were, after talks took place and a negotiated settlement - the Strathclyde Manning Agreement, was made. This made sure a Guard (repurposed as a Ticket Examiner) was rostered to every train, but the trains operated as DOO and could run without a Ticket Examiner in circumstances when one wasn't available. The Southern agreement with ASLEF as to when trains could run without an OBS was along similar lines.
Here's a press cutting from the time:
I'm sure I read that it was free to use Strayhclyde trains for a week shortly afterwards, as an apology to the public for putting up with the strikes.
The South West part of Network South East and the Euston to Northampton lines had some platform furniture (mirrors or monitors) fitted, but there was much resistance by the workforce to conversion, and progress halted due to their positioning not being optimal. Privatisation came, and the new managements thought it too much hard work to continue to push it through.