Noisy cold water pipe

[LionelB007]

Due to our kitchen being refitted the mains cold water supply has been moved to a new location 12 inches from the original location. Now when I use any cold tap in the house I hear a rumbling whining sound. My plumber tells me that he has used the original stopcock and pipe so this sound must be trapped air. This sound has been going on for days and days surly any trapped air would have gone by now?

 

[Aquarius]

Trapped air is as the name suggests, trapped, so not necessarily released. Is the stopcock fully open? Are there any vertical rises in pipework that remain capped?