Noise after flushing toilet

Hi
I would really appreciate if anyone could offer any advice on this.
I'm in a 3 bed semi-d, 1 bathroom upstairs, toilet downstairs, re-plumbed 6 years ago, pumped system.
For several weeks now, everytime either toilet is flushed, a few seconds later a loud humming noise begins and continues for about a minute. If it's the upstairs toilet, the noise will stop temporarily when the tap is turned on.
My husband tried restricting the flow into the cistern of the downstairs toilet (with a clothes peg on the plastic pipe in the cistern) - this seemed to reduce the noise from the downstairs loo alright but not completely.
Then on the advice of our plumber, we replaced the ballcock in the tank in the attic - this had little or no impact.
Is there anything else we can try before having to get a plumber in?
TIA
Dannad

sounds like water hammer...is the noise coming from the attic? are all the pipes in and out of the water tank secured tightly?
I have the same problem and cannot get it solved despite having had 3 different people look at it...i was finally told it's down to the water pressure from the mains

Noisy loo

We had this problem also. The racket reverberated thru the house after d st loo flushed and lasted several minutes but would stop if nearby tap turned on. We thought it might be some problem in attic and storage tank but in fact it was a valve or washer in the the cystern of the loo and sorted by a plumber who replaced same. Just a bit of black rubber. I think this has already been discussed here?

I had this issue and resolved it by replacing the flexi hoses under sinks. A kink in he flexihose was causing the water to vibrate under pressure. Once the flexi connections were changed to copper or smaller flexi connections the issue went away

Had this problem also. I went into the loft and had my wife flush the loo so I could tell which pipe was 'hammering'. I just moved it slightly (literally a few millimeters) and put a wedge against it to hold it taught in position. Problem solved.