.. How odd ! I posted about this the other week as I live by the Bricklayers arms and heard these mysterious sounds which woke me up at 4am on a Saturday morning. I thought it might be a Fog horn and it kept going at five minute intervals for about ten seconds at a time. I opened my bedroom window and it seemed to be coming from Bermondsey on the Tower Bridge Road side. After several replies onto my post the sounds remain a mystery !
At 4am every morning we get a soft sort of hum,it's quite loud and wakes me up sometimes,this is in St Geordes circus area,lasts about 10 minutes and then goes intermittent for about 20 mins,driving me mad it is,I never related it to the bricklayers noise before,this noise feels more local than that,interesting!
It's every morning,without fail and has been going for a month or so that I know of.
boroughonian, it sounded very local to me as well but was difficult to pin point any exact location but it must be the same thing and covers a wider area than whlsarah or me I guess. It drove be bonkers as well I had to go to the sitting room to get some quiet it was that bad. I have not heard it since for about three weeks but I am now convinced by your description that is what I heard as well but it's interesting you are hearing a hum so it may be more over your way the source .. all very very mysterious indeed.
Micky,well I said it's been going about a month but it could be three weeks,it's on the move!
I'd say it was alto.
PS: actually,thinking about it,it could well be on the move and a railway thing?
PPS:I'm going mad,Micky I used to live at the Brick and remember the noise your talking about,it was like a fog horn and sounded closer than the Thames but that's all I could think of,that's going back over 10 years,i've just mentined it to the Mrs,she remembers it too.