There has only been one by-election so far this parliament for a seat in Westminster, which was won by Labour in leader Jeremy Corbyn's first national electoral test.
But there have been many more council by-elections since Corbyn took the reins of the Labour party, and there is a distinct regional pattern to how Labour has performed since September.
The data, gathered by Labour List, a blog for centre-left issues, shows the change in Labour vote share in all the council by-elections where there has been a Labour candidate - as well as a Labour candidate in the previous contest so a comparison can be made - since the leadership election in September.
The results are grouped into regions so that it is possible to observe a regional pattern. As shown in the map, Labour is doing better in London under Corbyn, but worse almost everywhere else.
The data is taken from each by-election and then grouped into regions, with each region's vote share change being averaged. There have been some 68 council by-elections since the leadership election.
In London, Labour has gained most prominently in South Camberwell, Southwark, gaining a further nine per cent in vote share, and Boleyn, Newham, where the party gained 7.9 per cent. Labour, however, struggled in Westminster, where they lost 5.7 per cent of the vote share from the previous election.
Meanwhile, there was no change in the Labour vote in the South West, and marginal gains of 0.1 per cent in Wales and Yorkshire and the Humber.
In Scotland, where Labour will be hoping to recoup some losses made to the Scottish National Party, Labour lost vote share in nine out of 10 of the by-elections.
So, while it's a long way off yet until the next General Election, Labour will need to turn their fortunes and make gains where the Conservatives and the Scottish National Party are strong if they are to form the next government.