Many years later the entrance in the photo above was built - joining up not with a road or cycle path but with some waste ground at the other side next to a disused railway. The photo shows how the cycle and pedestrian entrance to the Cambridge Science Park is closed during night-time hours for "security reasons".
The answer to this mystery is to be found in sociology. In societies like the UK's, where only a small number of people cycle, cyclists are an out-group. Apart from cyclists being considered to be on the edges of society, and quite possibly criminal, cyclists also suffer from homogeneity bias. An example of this is the way in which newspapers in the UK often carry accusations of cyclists "all" being law-breakers.
Well intentioned campaigns to improve the position of cyclists in society by improving their behaviour, such as those to encourage cyclists to always stop at red traffic lights fail due to a mis-understanding of what causes cyclists to be disliked in the first place.
While many people in places with little cycling may express that they dislike cyclists because of such things as going through red lights, this is simply an expression of a dislike due to cyclists being cyclists. If it were not red lights that they commented on, it would be something else (as demonstrated by this letter, or this one). In some places, even providing sidewalks is thought to draw in undesirables (see comments here).
There is only one way to improve the public perception of cyclists, and that is to make cycling attractive enough that everyone becomes a cyclist. For this to be the case, cycling must be safe as well as direct and convenient.
Of course, some cyclists genuinely are outlaws. Here's a video of Great Train Robber Bruce Reynolds talking about cycling. But bear in mind that while some outlaws are cyclists, that does not imply that all cyclists are outlaws:
Read other posts about campaigning for more cycling when cyclists are an out-group.
To illustrate this phenomena I had to use a photo taken when we still lived in Cambridge and links to letters to the newspaper there as this sort of thing simply doesn't happen here. In this society, cycling is a normal thing. It is part of everyone's life. As a result, newspaper letters pages and editorials are free of complaints about "outlaw cyclists" even though the actual behaviour of cyclists here is quite similar to elsewhere, and there are no arbitrary restrictions against cyclists. Quite the reverse in fact.