A Prime Minister Burnham could legally hold a referendum on proportional representation in 2028 if Parliament passes enabling legislation. There is no legal barrier to doing so—the 2011 Alternative Vote referendum demonstrates that a UK-wide voting-system referendum can be legislated and held within a single parliamentary term. A referendum result would be advisory under UK constitutional practice, meaning Parliament would still need to pass primary legislation to implement any change [1].

However, moving from a 2028 referendum to a fully operational new electoral system by the 2029 general election would be extraordinarily ambitious and faces severe practical obstacles. The next UK general election must be held no later than 15 August 2029, with automatic dissolution on 9 July 2029 [2]. This leaves a narrow window for implementation. The specific challenges depend on which PR system is chosen. Systems requiring new multi-member constituencies (such as Single Transferable Vote) would need boundary redrawing, which typically takes two to three years including statutory consultation and independent oversight [3]. Even faster options, such as regional list systems using existing boundaries, would still require detailed implementing legislation, Electoral Commission guidance, secondary regulations, ballot design, and staff training—all within roughly one year.

The 2011 AV referendum is a limited precedent because it retained existing single-member constituencies and required no boundary changes, understating the administrative effort needed for most PR models. A government attempting this timeline would need overwhelming parliamentary majorities, cross-party consensus, and flawless execution. If the process slips at any stage—legislative delays, legal challenges, or administrative complications—the 2029 election would likely proceed under the existing First Past the Post system. In summary: the referendum is feasible; full implementation by 2029 is legally possible but practically improbable without unprecedented speed and political alignment.