Radio Interference - how can I track down the source?

[London GT3]

About six weeks ago I started having trouble with operating our front gate with the clickers and opening/locking cars with the remote key fobs (not all cars but some worse than others). The gate clickers won't work unless they are right on top of the receiver. The car clickers are a bit mixed but many wont work unless they are right close up on the cars. Some don't work at all. Others work fine. Neighbours have reported problems locking cars in the vicinity.

I have renewed the batteries in all the gate clickers. The gate maintenance company has been out to the gate and they are baffled.

Something is interfering with the signals. I have isolated everything in my house so I know it doesn't emanate from there. There are lots of other houses around so I am guessing that one of them has installed something new that may be the cause. However, if I can't identify where it is coming from, I am at a loss to do anything about it.

Is there a piece of equipment that would be able to detect a strong radio signal in the area and give some idea of the direction from which it is coming?

Thanks.

[London GT3]

I'll disconnect all the WiFi at the weekend but I don't think that is the problem. I have switched everything off at the mains and the cars still won't lock/unlock.