When the 18 first-year delegates to the General Assembly are sworn in next month, at least one of them will be regarded with particular interest by his fellow legislators.

To be sure the three new black delegates (who will bring the total of black delegates to four) and the three new women delegates (now there will be nine) will be the most visible. But the new kid in school who will be eyed with curiosity is a white, Anglo-Saxon male, Robert L. Thoburn, the new gentleman from Fairfax.

This is the conservative Republican whom Democratic gubernatorial candidate Henry E. Howell described as a "Siamese twin to a caveman." This is the man who has made the defeat of the Equal Rights Amendment a top priority, and the only delegate (according to him) from Fairfax who, at a recent caucus, opposed a proposed bill to give the county a charter.

Thoburn once outraged a group of women by suggesting at a women's commission hearing on crime that a law be enacted requiring a "seduction dowry," whereby a man who seduced a woman be forced to marry her if her parents deemed him a suitable husband, and pay restitution to her if he was not. He says he favors the death penalty for anyone convicted of rape.

He infuriated Democrats during the campaign with a brochure that implied voters had a choice between him and a Democrat when in fact there were 11 candidates seeking the five seats. The Fairfax County Fair Campaign Practices Commission found him guilty of violating its code. But since the commission ruled after the election and can impose no penalities, the ruling amounted to a mild slap on the wrist.In any event, Thoburn had refused to sign the code during the election in the first place.

Thoburn is a businessman and the owner of the Fairfax Christian School. He is a clergyman with degrees in theology and divinity. He is also a proud conservative who plans to run for Congress in two years (Herb Harris's seat), a bid he made unsuccessfully in the last congressional primary.

Thoburn believes the federal government plays too large a role in the average person's life. He runs his school as a business rather than as a non-profit corporation and sends his eight children to private schools because "I reject all forms of aid." His ultimate goals is tot get the state to do likewise.

"The federal government controls states by threatening to take away their money," he said, "We tend to turn to the federal government for aid to avoid the responsibility of levying taxes. I think it's time some (state) governments say 'we won't take federal money.'"

The leadership to achieve such a rejection of federal help would, he modestly admits, take "political courage," leadership he is prepared to provide. But ultimately, he said, an effective attack would be made through this type of action on the "number-one problem" facing the country today - inflation.

Thoburn likes to draw attention to what he considers to be excessive government costs. For example, at a recent orientation session for new legislators he asked, "How much does it cost to put in a bill?" a remark that was interpreted as an indication that Thoburn thought a legislator had to pay a fee to introduce legislation.

What he really wanted to know was the administrative costs of introducing legislation - the salaries of the legislative researchers who write most of the bills, the cost of printing, distributing and so forth. He was given an estimate of $100 per bill, which he thinks is low. Other legislators think the question is useless because it is not really possible to measure such a cost.

He would like to introduce legislation that says simply: "Thou Shalt Not Steal." This was inspired by a letter from a constituent. The constituent was a travel agent who had made good on a bad check from a customer to an airline but then discovered he couldn't prosecute the paperhanger because the law covers, according to the constituent's report, bad checks for goods but not services.

Thoburn and fellow Republican Robert Harris are the only members of the 27-person Northern Virginia delegation of senators and delegates who oppose the Equal Rights Amendment, and Thoburn predicts the ERA will again be defeated.

"We aren't expecting it to be easy, though," he said.

Thoburn already has met with conservative Independent Eva Scott from Dinwiddie, who is one of the more ardent opponents of the measure. He, Scott and Alyse O'Neill, who heads STOP-ERA in Virginia, met recently with former majority leader james M. Thomson, who was defeated by pro-ERA supporters in Alexandria. Thoborn said they met to ask Thomson for advice.

Thomson, however, said they didn't really need advice because "there's no way the Virginia General Assembly is going to pass the ERA. The votes just aren't there."

It will be interesting to see how all the new delegates get through their first confrontation with that unwiedly lawmaking body called the General Assembly. It will be particularly interesting to watch an avowed congressional candidate with such a specific ideology.