NR, another thought. Are you and boy-wonder using antennas in same polarisation? if he's holding his w/t upright with the antenna vertical, and your loft antenna is mounted horizontally, this will have a big effect on close range signal strength.... If I remember rightly the attenuation of signal with 90 degree out of alignment antennas is in the order of 20db!!!
Bet to rig your dipole with the shield of the coax connecting to the lower element and the centre core to the upper element. Try to ensure the feed line approaches the dipole at 90 degrees to the elements.
This is an N Type to SMA connector, but they are buggers to solder onto coax, so maybe get stuck into your shortening of coax and polarisation and location of dipole first, as the additional gains of this sort of connector may be unnecessary:
http://www.ebay.co.uk/itm/N-Type-Male-Ja...20d58ea1a1