Stephen Osborn wrote to uk.transport.london on Sat, 1 Jan 2005:
The flash change over for London numbers (from 0171 xxx xxxx to 020 7xxx
xxxx) was at 1 am on 22nd April 2000.
That was Easter Saturday so there more time than usual to sort out any
problems, also the network load the following week would be lower than
normal.
But right from the beginning of that year you could dial 020 7xxx xxxx
or 020 8xxx xxxx, and you programmed your phone like that so that you
didn't have a problem on the Tuesday of Easter week. At least, we did
where I worked.
--
"Mrs Redboots"
http://www.amsmyth.demon.co.uk/
Website updated 18 December 2004