A WDB FLC IN A FOREIGN COUNTRY MISUNDERSTAND CLRNC TO TAXI INTO POS AND HOLD AND TAKE THE ACTIVE RWY IN FRONT OF A LNDG ACR. THE LNDG ACR WAS ISSUED A MISSED APCH. THE CTLR CLAIMS THAT THE CLRNC WAS TO LINE UP ON RWY 8R AFTER THE LNDG TFC. THE RPTR DID NOT HEAR 'AFTER.'

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WE WERE HOLDING SHORT OF RWY 8R ON 'E SOUTH' TXWY AT LONDON'S GATWICK ARPT. 2 OTHER HVY JETS HAD JUST TAKEN OFF WITH VERY TIGHT DEP SPACING AND THERE WAS NO TFC I COULD SEE ON FINAL. AS SOON AS THE JET BEFORE US WAS AIRBORNE; BOTH MY CAPT AND I UNDERSTOOD THE TWR CTLR TO SAY: '(OUR CALL SIGN); TFC (ACFT CALL SIGN/TYPE) ON A 3 1/2 MI FINAL; LINE-UP RWY 8R.' I SPECIFICALLY READ BACK: '(OUR CALL SIGN); CLRED TO LINE-UP RWY 8R;' WITH NO MENTION OF A CONDITIONAL CLRNC. I LOOKED AGAIN FOR TFC AND SAW THE FINAL APCH TFC JUST UNDER THE CLOUDS ABOUT 3 MI OUT. I THOUGHT THERE WAS AMPLE SPACING FOR OUR TKOF BTWN THE DEPARTING AND ARRIVING TFC AND EXPECTED TWR TO CLR US FOR TKOF AS WE TAXIED INTO POS. WE THEN TAXIED ONTO THE RWY AND HELD IN POS FOR TKOF WHILE THE JET IN FRONT OF US DEPARTED. AFTER ABOUT 1 MIN SINCE RECEIVING OUR RWY LINE-UP CLRNC; THE TWR ABRUPTLY TOLD THE ACFT ON FINAL APCH TO GAR AND TOLD US THAT HE HAD CLRED US TO LINE-UP ON RWY 8R AFTER THE FINAL APCH HAD LANDED. WE WERE THEN CLRED FOR TKOF AND NO OTHER WORDS ABOUT THE CONFLICT WERE SAID BTWN THE TWR AND US. I DON'T KNOW EXACTLY WHAT CAUSED THIS INCIDENT. A REVIEW OF THE TWR RADIO TAPE RECORDING WOULD PROBABLY CLR UP THE MATTER. IT WAS EITHER: 1) WE POSSIBLY MISUNDERSTOOD THE CLRNC. THE TWR CTLR HAD AN ENGLISH ACCENT; USED ATC TERMINOLOGY THAT DIFFERS FROM THE FAA'S; AND SPOKE FAIRLY FAST. WE WERE ANTICIPATING A TIGHT DEP SPACING CLRNC AND INITIALLY DID NOT SEE ANY OTHER TFC ON FINAL. OUR ANTICIPATION MAY HAVE SET US UP FOR HEARING WHAT WE WANTED TO HEAR. PLUS; WE WERE OPERATING ON THE 'BACK SIDE OF THE CLOCK' BODY TIME SINCE WE AWOKE AT XA00 AM CENTRAL DAYLIGHT TIME AFTER A DUTY DAY THAT ENDED AT XC00 AM CDT THE DAY BEFORE. 2) IT IS POSSIBLE THE TWR CTLR MISSPOKE AND THOUGHT HE SAID 'AFTER TFC LANDS; LINE-UP RWY 8R' BUT IN FACT DID NOT SAY 'AFTER.' 3) THE TWR CTLR PERHAPS DID SAY 'AFTER' BUT HIS RADIO CALL WAS GARBLED OR THE WORD 'AFTER' WAS CLIPPED OFF DUE TO CLICKING THE MIKE LATE. 4) THE TWR CTLR MAY HAVE FORGOT HE CLRED US ONLY TO LINE UP AND WAITED TOO LONG TO CLR US FOR TKOF THUS CREATING A TFC CONFLICT. WHATEVER THE REASON FOR THIS INCIDENT; IF THE EUROPEAN CTLRS WOULD FOLLOW STANDARD FAA PHRASEOLOGY OF NOT USING CONDITIONAL TKOF AND LNDG CLRNCS; THIS TFC CONFLICT WOULD NOT HAVE OCCURRED. CONDITIONAL CLRNCS ARE 'ACCIDENTS WAITING TO HAPPEN' AND RELY ON PERFECT COMS BTWN AIRCREWS AND CTLRS. WHEN AIRCREWS READ BACK CLRNCS WITHOUT REPEATING THE CONDITIONS ATTACHED (AS I DID); THE CTLRS SHOULD IMMEDIATELY CLARIFY THE CLRNC SO THERE IS NO MISUNDERSTANDING. THE BOTTOM LINE IS CONDITIONAL CLRNCS SHOULD BE PROHIBITED.