The suggestion for a new town (by a think-tank rather than the Government) at Tempsford is overly simplistic and flawed. The suggestion is based on the current proposal to site the ECML/EWR interchange station nearby, but this plan is equally flawed.
Far better to route EWR through the existing St Neots station (which can accommodate the additional two lines with only minimal changes to the existing island platforms; ticket office; pedestrian bridge; lifts etc) and make St Neots the interchange station. The town already has the third-largest population in Cambridgeshire (after Peterborough and Cambridge) and could provide 33,000 (& growing) potential customers for EWR from its first day of operation. Far more sensible to build the required homes around an existing town, which already has the necessary services (albeit that would need to be expanded). In contrast, even if Tempsford New Town was built twice as fast as Cambourne, it will still only have 25,000 potential customers by around 2050. St Neots is likely to have a population closer to 50,000 by 2050.
The new A421 (currently being built between the Black Cat Roundabout/A1 and Caxton Gibbet) makes no provision for a new town. Highways England's plans do not include any additional connections to Tempsford, so all traffic would be forced onto the existing roundabouts (A1 & Barford Road - St Neots).
It is possible, that Highways England are aware of the flood prone nature of the Tempsford site (on the banks of the River Great Ouse), but even HE could not have anticipated the amount of flooding in the area in 2024. At the next measuring station (Eaton Socon - St Neots) downstream from the Tempsford site, the River Great Ouse has exceeded its 'highest recorded level' twice in the last twelve months. The think tank is clearly unaware of this, and that as well as the main spans of Roxton Bridge (near Tempsford), there are fourteen flood arches to accommodate the river when it becomes swollen and overtops flood defences.
In addition, not only do locals living in Tempsford, not want their village to be swamped by the building of thousands of homes, they don't want EWR or its station. In contrast, over 1600 people have already signed a petition calling for EWR to be routed via St Neots.
https://you.38degrees.org.uk/petitions/connect-st-neots-to-cambridge
It would also be fairer to expand St Neots, because at least the increased Council Tax revenue would be spent in/on the town. BEDS Council has/is planning thousands of homes at Tempsford; Dennybrook and Little Barford (all on the border with Cambridgeshire and a 'stones's throw' from St Neots). It is unfair and quite frankly devious, of BEDS Council to do this, knowing that immediate demands for public services as well as increased congestion etc, will fall on St Neots, yet BEDS Council will gain the additional Council Tax revenue.
Finally, before I'm accused of being a NIMBY, I would like to point out that I live in St Neots. Despite living on the very southern edge of the town (i.e. closest to the proposed EWR station at Tempsford), the planned station will not be convenient to reach; nor time-saving to use and will not tempt me out of my car. I believe St Neots should be the interchange station and accordingly, I have signed the above-mentioned petition.