Currently, Wikipedia lists the following parties as centre to centre left:

• Labour

• Liberal Democrats

• Scottish National Party

• Green Party

• Plaid Cymru

• SDLP

• Alliance Party

New parties that are considered to be centre to centre-left may be added to this list at my discretion; I will also evaluate independent candidates.

Sinn Féin is excluded from this list because of their abstentionism.

If this market was resolved at the time of creation, it would resolve between 504 and 507 (399 Labour + 72 Liberal Democrats + 9 Scottish National Party + 4 Green Party + 4 Plaid Cymru + 2 SDLP + 1 Alliance + 13-16 independents)