the odd thing was ,i took out all the neutral's and had a dead short between neutral and earth i then switch of the main isolator and the dead short went

With your  N connected to the supply (i.e. with main switch in the ON position) - N will always be connected to true earth via the supply arrangements (N is deliberately earthed at the transformer at the very least - often at many more places too via additional PME electrodes and other consumer's bonding). So there will be some continuity from N through true Earth to your TT electrode and hence to your Earth bar - in the region of your 205 Ohms - or 0.000205MΩ - which will show on most insulation meters as 0.00 or a dead short.

   - Andy.

When Paul Berryman said that he had a "dead short" I took it to mean that he had used a low resistance ohmmeter rather than an insulation tester.

However, why was a dead test done with the main switch closed? (I am asking him, not Andy.)

When Paul Berryman said that he had a "dead short" I took it to mean that he had used a low resistance ohmmeter rather than an insulation tester.

However, why was a dead test done with the main switch closed? (I am asking him, not Andy.)

because its a split board and there is two rcd after the main switch