Accepting that the prosecution case has merit has always involved the setting aside of certain sets of facts as "pure coincidences".

The most extreme of these has been that the Lockerbie flight-time was 38 minutes.

Now it seems that Public Interest Immunity (PII) certificates are being used to "protect" from the defence's scrutiny the one forensic item which seems to support the 38 minutes being an extreme coincidence, rather than a terrorist's expected outcome (The Herald, February 21).

This 38 minutes perfectly matched the inevitable time of explosion had a Syrian fixed-timer device been put aboard at Heathrow, yet this timing seemed extraordinarily unlikely to have been used by a terrorist with a fully-adjustable Swiss-made timer initiated in Malta.

Why would a terrorist in Malta use a time setting that would only clear Heathrow by 38 minutes, when his alleged device was perfectly capable of lasting until the aircraft would be well out over the Atlantic? And in December, just before Christmas with two changes of aircraft and endless possibilities for delayed flights?

The only "evidence" that a Swiss timer had been used was a small piece of timer circuit board, shown at Zeist as "PT35B".

Dumfries and Galloway Police (D&G) are in possession of a document from a "foreign power" for the custody of which, as for PT35B, they are responsible. This is the very same "foreign power" document whose contents the Crown and the advocate-general are seeking to keep concealed from the defence (and the public).

Yet it has also emerged that D&G has been in possession of the document since long before the Zeist court case. If, as is widely believed, this document bears upon PT35B, it may be that the D&G difficulty over explaining PT35B's provenance in Zeist was influenced by something they had learned about PT35B from their perusal of the "foreign power" document.

Three consequences follow: First, if the integrity of the D&G performance at Zeist is to be fairly assessed, the contents of the document must be known to both sides in the dispute, and debated in front of the Appeal Court. Remember that the contents of this document appear to have been relevant to the SCCRC's decision that the case should be referred back.

Second, the provision of the document to D&G well before the Zeist trial, and their current possession of a copy of it (already admitted at a previous hearing of the High Court where they were directly represented) is in itself a major breach of the confidentiality currently being used as a reason for the preparation of PII documents by the Foreign Office in London.

Third, the failure of Mssrs Hayes and Feraday to forensically examine PT35B before the Zeist trial indicates how important it is that the defence be granted full forensic access to this and all productions now, as petitioned in the High Court.

Confidentiality seems already to have been hopelessly breached.

Dr Jim Swire (father of Flora, murdered at Lockerbie), Chipping Campden.