Re: Sour grapes?
When I was running an IT team supporting a large unitary, the reason that I would go to tender rather than build, is time, risk and cost.
Despite being an ex-coder myself, and enjoying designing and building stuff, as an IT manager my approach was always "can we buy" first, and only then "can we build it"
Off the Shelf kit is always going to be cheaper than DIY, usually between half the price, to 1/10th, dependant on the size of that market (i.e. Planning systems are only needed in planning authorities)
If you use software used by 100 identical authorities, all the "features" of the system have been found and worked round, and deployment time is constrained by duration of ITT, and availability of installers and staff for training.
My in-house team got used for stuff that was unquie, hence one of the selling points for working for 70% of what you could get at a comercial IT shop, was lots of different and interesting work, that makes a difference (on ocaasion potentially life saving differences)
Some times the UK/EU procurement rules get a bit daft if enforced to the letter of the law, and your head of procurement is unwilling to sign waivers, ie. you should not have to advertise for the better part of 3 months, when there are only 2 companies with the software ready to go.