Immigrationboards.com

The immigration rules say

section 6.3.7.3
For adult applications each referee should have known the
applicant personally for at least 3 years

Does this mean that office work colleages cannot be refrees ?
Has someone been successful with refrees only as office colleagues ? Both my refrees are from the same office where I worked.
Will this be a problem ?

Don't think this should be a problem. Colleagues can know you personally.

Just make sure that other conditions about the referees are met.

Several of my friends and myself, we all used colleagues as references - all approved without any issues.