Note to self take your own advice and don't use ferrules with spring terminals*. Despite first crimping them on the wire pulled out of the ferrule. After getting the ferrule out I reverted to strip and insert bare conductors. Note to self: only use ferrules with screw terminals.
* These were big professional spring terminals with a high clamp force. A screwdriver is inserted in an adjacent hole to depress the spring and allow insertion of up to 6 mm sq. stranded conductors I thought ferrules would make things easier/neater for the 1mm stranded I was using.
I lost track of what you were saying there!
Anyway, I got some ferrules (massive box of all sizes for £8, you know where) - job is now done and all worked: cut cable from mains, stripped and crimped on ferrules (with extra long bare wire in the metal part), nipped the end of the ferrule metal parts as they were a shade too long for the choc-blocks, attached new lights with short cable tails to the choc-blocks, tested and refitted to the ceiling. Easier than expected, only one of the ceiling holes needed a very minor touch-up on the plaster.
... even better, the halogens downlighters I removed were all working, 19 of them - listed on Gumtree and sold in 10 minutes
- that cash covered the cost of all the GU9 LED bulbs I've bought to replace halogens in a load of other wall and ceiling lights around the house. Result.