It is possible to lengthen the Romford axles, access to a lathe is the best way, but it can be done without. All axles will have to be installed in horn blocks for it to work as the axle cannot be slid through the bearings when done.
Like Mr Holman style with his Gauge O axles
Chop the axle in half and sleeve it with a turned brass sleeve bored out to a close fit on the axle with allowance for the bearings, size and Loctite together in a V block, if no lathe use KS 5/32'' tube, the internal diameter is almost correct and the Loctite makes up the difference. Use off-cuts of the tube to support the axle ends in the V Block while gluing. Lining up the square ends is the critical bit- a gauge can be made to do this. One can also use a set of wheels to do the lining up but a narrow V Block is required that does not foul the wheels.
The drive axle can be sized by using the drive gear, Scale Link do a wide sleeved gear in their SLGS03 set, if you calculate where the grub screw hits cut this axle so that the screw locks onto one side of the cut axle, for maximum coolness a second grub can be installed to catch the other side of the cut axle. The above sizing gauge should be made deep enough to allow for the gear when lining up the square ends. Put in the grubs after the glue has set and do file a flat on the axles for the grub to land on.
oops! only file a flat on one side for the grub if doing the 'Two-Grub'
Eoin