Apologies, I haven't read the whole thread.
These are my views:
The garage is in a "courtyard next door".
Is it in a block?
In London that is perfectly acceptable.
In Colchester at nearly £700k, not acceptable.
It has a tiny garden.
In London, perfectly acceptable.
In Colchester it may appeal to the older generation who find gardening too much, but hold on, it's got two staircases/3 floor, so maybe the older generation wouldn't be suited to it.
For families with young children, I think they would be looking for a bigger garden. Also some parents may not want to have their children on a different floor to them.
The property has been heavily extended and updated, so potential DIYers may not feel challenged to put their own stamp and upgrade on a property at the top of the price range already.
I understand it is actually a Victorian property. Unfortunately, it looks like a new build and, of course, there are many potential purchasers who prefer character properties. Perhaps they don't realise that this isn't a new build as it's not obvious.
Colchester is commutable to London, but season tickets will be expensive and the commute will be approximately 1 hour on the train.
The property was advertised for £700k in December 2021.
In 9 months, you have reduced the price by only £20k.
Lexden may be a desirable part of Colchester, but there are other areas in Essex which would offer more space and in a prettier location.
For context, I live not too far from you and I think it is overpriced.