The BBC's Lynley page just states...
"
In a change to the schedule, the billed episode on 16/08/07 was replaced with a repeat from last year. The new series will be shown at a later date. We are sorry for any frustration this may cause."
However the BBC issued a statement on 14th Aug in response to the previous week's episode being replaced with a repeat after complaints that no reason was given by the continuity announcement...
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Due to similarities between the billed episode and further developments in the Madeleine McCann case reported in the news that day, the decision was taken to replace the planned episode with a repeat from last year.
It is standard practice on occasions like this for the continuity announcer to inform of a change of billings, but it was felt that it would be inappropriate to go into a more detailed explanation.
The new two-part series will be broadcast at a later date to be confirmed, meaning that the episode billed to transmit on 16 August will also be replaced by another programme. Again, we are sorry for any frustration this may cause.
We acknowledge there was no apology in the announcement on 9 August but we will be including one in the announcement on 16 August."
http://www.bbc.co.uk/complaints/news/2007/08/1 4/47873.shtml