Only two doctors' surgeries in the wider Northampton area offer full seven-day a week access - four years after the Government announced plans to improve GP opening hours.
In 2014, the Government pledged to introduce extended opening hours at GP surgeries across the country.
Then Prime Minister David Cameron said the Conservative Party would ensure that "everyone” could see a GP seven days a week by 2020.
"We will support thousands more practices to stay open longer - giving millions of patients better access to their doctor," he told a 2014 party conference.
But analysis by the BBC Shared Data Unit has revealed that, in England, only 41 per cent of GP practices offer “full provision” for extended appointments outside of normal working hours and weekends.
Shadow health secretary Jonathan Ashworth MP, said this was "evidence that the Tories have broken their promises on access to GPs seven days a week."
"The truth is that years of austerity has taken its toll on general practice," he added.
"We need a serious long-term investment plan for primary care.”
The figures show that only two practices out of the 53 to respond to an official survey in the Nene CCG (Clinical Commissioning Group) area, offered the so-called "full provision" for extended access.
Nene CCG is the health body in charge of 68 GP surgeries in Northamptonshire, except for Corby.
It means that only 17,228 of the 567,966 patients registered with the commissioning group have access to pre-bookable appointments on a Saturday and on Sundays; early morning appointments before 8am and evening appointments after 6.30pm.
In total, 10 practices offered no extra provision at all outside of normal working hours.
However, 82 per cent of Nene CCG’s patients can access out-of-hours appointments on at least one day a week.
At Corby CCG, no surgeries offer the full provision; four offer partial provision and one offers no provision at all.
In an update to its plans for 2018/19, NHS England and NHS Improvement said it had a set target of October 1, 2018 for all patients to have access to extended hours, instead of the end of March 2019 as originally planned.
From this date, it will be mandatory for all Clinical Commissioning Groups (CCGs) to put in place arrangements for extended access to general practice. However, it will not be obligatory for individual GPs to provide the access.
A spokesperson for Nene CCG said: “We are on track to mobilise extended access in practices in line with the national target of 1st October 2018.”
An NHS England spokesman added: “The NHS is investing at least £258m this year to offer improved access to general practice, including evening and weekend appointments. This is ahead of schedule with appointments available to more than half the country now, and they will be available across the whole country by October this year.
“The 55% figure quoted in the planning guidance is based on data collected through the GP Forward View monitoring survey, which is completed by CCGs. This reflects the provision of extended access, including evening and weekend appointments, available to the local population over and above GP appointments available during normal working hours.
“The 40% figure (seen in the open data analysed by the BBC Shared Data Unit) comes from the latest results of the extended access bi-annual survey, which collects information on extended access from individual GP practices, not all of which will provide evening and weekend appointments, as these may be provided through access hubs.”