One is IMHO more likely to get a transit (or indeed a radar service OCAS) if one sounds like one is on the ball. This means
- IFR rather than VFR
- reading off an "obviously IFR" route e.g. one based on intersections/navaids rather than silly village names
- on the ball radio manner
I think UK ATC denies (officially) there is any effect but they cannot possibly deny it abroad