Letter-bomb at No. 10 Downing embarrasses British officials

Concern. Embarrassment. A dismissal of fanciful reports and exaggerations of damage to United States, British, and NATO security interests.

That is the mood of British officials here as they contemplate a spate of intelligence and security failures in recent months - capped by the first letter-bomb ever to penetrate into No. 10 Downing Street itself.

Officials readily concede that the British government is embarrassed at the way security cases have coincided to make headlines recently, and that the Reagan administration in Washington has been concerned. Britain says it has kept Washington briefed all along.

They also agree that it is difficult for the public to sort out which cases are serious and which are not.

Meanwhile, the press here is criticizing the government for domestic security lapses - from the man who gained entry to the Queen's bedroom earlier this year to the letter-bomb which went off inside 10 Downing Street Nov. 30, lightly injuring office manager Peter Taylor.

No extra security was visible to visitors to No. 10 the next day, though the lobby inside was more crowded than usual with guards. An electronic screening device is being considered for use inside. Officials say all mail for No. 10 is pre-checked by nearby post office.

Between 2,000 and 3,000 letters are addressed to the prime minister every week. This has jumped lately as animal lovers have poured out protests against the season of hunting seals and their cubs.

The animal rights militia, which signed the note inside the letter-bomb, is unknown to other animal groups here.