The initial answer is "watch this space". However, one outcome, hopefully and in the long term, will be to decrease the congestion on the Lincoln Road especially at peak times.
Update: The Sleaford Town Council debated two main issues relating to Boston Road on Wednesday 5th July. Firstly about Bikers using the Rec once per month and secondly the public comments/reaction to the proposed access to Boston Road from the Advanta Seeds site. The link to the Youtube recording of that part of the meeting is HERE.
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Interestingly there was a short mention of it (the talks with Tesco by STC) at last weeks Council Meeting (21st June).
This was at Agenda Item 14.2 and was recorded.
However I have attached, as a link at the end, a Radio Interview back in 2013, on Radio Lincolnshire, between the Mayor (at the time), and our present County Councillor (Kate Cook).
The YouTube Link is at: Boston Road Site Access.
How times have changed. (Hopefully). Some trees have been marked, presumably those under threat, but they relate (to my knowledge) what was proposed at the time of the CPO (2014/2015).