Former Rhodesian prime minister Ian Smith arrived today for the constitutional conference on Zimbabwe-Rhodesia, setting foot in Britain for the first time since he declared the African colony independent 14 years ago.

The conference opening Monday has its ironies for the British, many of whom -- having seen the sun set on the Empire -- would like to be done with the recurrent Rhodesian problem of which Smith is a symbol.

Arriving at Heathrow Airport, the first notable Smith met was Britain's former prime minister, Harold Wilson, who was also the last official that Smith dealt with when talks on independence broke down in 1965 and led to Smith's unilateral declaration.

Today's meeting was strictly a happenstance. Wilson, 63, now Sir Harold, was at an airpot VIP lounge enroute to the United States for a lecture tour; Smith, 60, now a minister without portfolio in the new black-led government of Zimbabwe-Rhodesia, arrived at an adjacent VIP lounge amid heavy security.

Just the day before, the adjacent lounges had hosted two rival claimants to power in the southern African country, Prime Minister Abel Muzorewa and guerrila leader Joshua Nkomo.

On that occasion British protocol officials went to great lengths to keep the two apart.

Today, however, former combatants Smith and Wilson met as Sir Harold just "popped in" to talk for a couple minutes, in the words of an airport spokesman. "He said hello and wished him a successful conference," the spokesman added.

There are indications that the British would have preferred that Muzorewa leave Smith out of his delegation to the constitutional talks to try to settle the 14-year-old problem since Smith is so disliked by the opposition guerilla leaders.

Patriotic Front leader Robert Mugabe said Friday that he was "offended" by Smith's presence but would ignore it. Muzorewa called the man with whom he negotiated the country's internal settlement "a museum piece."

For most of the 230,000 white minority in Zimbabwe-Rhodesia, however, he is a hero and probably his approval is essential for them to go along willingly with any constitutional compromises.

Smith apparently intends to keep a low profile, thus lending credence to the impression that Muzorewa is indeed in charge, despite international refusal to recognize that blacks hold full power.

Unlike Muzorewa and Nkomo, Smith refused to hold a press conference. He did tell reporters on entering his hotel after passing about 100 anti-Smith demonstrators that he "would have been disappointed" if the protesters had not been there. About a dozen former Rhodesians were also on the sidewalk cheering him.

Meanwhile warplanes from Zimbabwe-Rhodesia today bombed an industrial and agricultural complex in Mozambique's rich Limpopo River Valley north of the capital city of Maputo, according to the Mozambican news agency AIM.

The agency quoted a military spokesman as saying the attack occurred while the Salisbury government was announcing the cessation of recent bombings. There was no response in Salisbury to the Mozambican report.