There were a number of proposals to electrify the line over many years but the 2012 proposal and announcement by the UK government was that it would include electrification of the railway line between Bedford, Wellingborough, Corby, Leicester, Derby, Nottingham and Sheffield. This sentence is a bit long and could be split up: The current programme of upgrades began in 2012, although electrification was proposed a number of times previously. The current programme includes electrification of the railway line between Bedford, Wellingborough, Corby, Leicester, Derby, Nottingham and Sheffield.

This was also part of a rolling programme of railway electrification projects. Does this need to be its own sentence?

To enable all the benefits of using electric traction, the line south of Bedford into London St Pancras is also being progressively upgraded including boosting the power supply Better wording/punctuation needed here

Parts of the line have been classed as congested infrastructure hence another reason for the upgrade.

The sections underway as of June 2024 are the electrification from Kettering to South Wigston as well as the upgrading of the overhead line equipment (OLE) south of Bedford to allow 125 mph (200 km/h) running. These two sections are due to finish construction in summer 2024 and late 2025 respectively. Needs update - Kettering to South Wigston has been energised. Additionally this paragraph could be reworded

The section of the line at the southern end between London St Pancras and Bedford was electrified with overhead line in the early 1980s and finished in 1983. This section is mainly a commuter route and is often called the Bedpan line. Could bedpan line be incorporated more naturally here? The section at the southern end of the line between London St Pancras and Bedford, nicknamed the Bedpan line, was electrified with overhead line in the early 1980s and completed in 1983. or alternatively the Bedpan line could be omitted entirely.

Then privatisation and a change in government intervened. This sentence is a bit awkward

In July 2009 the Labour government published a document and said it was looking at electrification of the Midland Main Line but no funds had been committed. Needs better punctiation

Ryan Scott the Network Rail Programme Engineering Manager was quoted as saying that the minimum number of platforms at Sheffield station – (Sheffield Midland) would be wired to avoid having unnecessary cost added when the station was later remodeled. The whole MML scheme also overlapped with the Electric Spine project. This is weird quotation style. A better style might be Network Rail Programme Engineering Manager, Ryan Scott, commented that the minimum number of platforms at Sheffield Midland would be wired, to avoid unnecessary cost added when the station was later remodeled.

In June 2015, the then Secretary of State for Transport Patrick McLoughlin informed Parliament the electrification project was being paused, resulting in criticism from local MPs. is worded weirdly - "the then" could be removed for the same effect

On 27 July 2017 a further briefing paper was issued and the Midland Main Line had a section of its own. Needs some commas

LAYOUT: Sections are appropriately ordered, no applicable specialised order. Images are appropriately sized. Article also uses emdash or endash where appropriate
WORDS TO WATCH: None used in the article.
FICTION: N/A
LISTS: Lists used thrice in article - once to list phases of the project, once as timeline, and once in further reading. Appropriate usage here.
However, Article does not have MOS:BOLDLEAD where it would be fairly easy to include, such as: