Red Runn, the three-time winner become british folk hero, has retired to a velvety round of personal appearance but the Grand National, world's greatest steeplechase, goes on and the Virginia-Maryland hunt circuit has a rooting interest in today's goings-on at Liverpool.

"American merchant banker Charlie Fenwick of Baltimore," as the dispatch from Liverpool quaintly portrays him, will be aboard Ben Nevis for the ride over 4 1/2 miles - barring a tumble over one of the 30 fearsome fences at Aintree.

Ben Nevis is tabbed third choice, at 14-1, by England's bookies. The steed began his career in point-to-point races in Britain, the swepted to 12 triumphs in the United States including the four-mile Maryland Hunt Cup twice.

Favored at 6-1: Alverton, winner of this season's Cheltenham Gold Cup - but there hasn't been a chelty-aintree double scored since 1934 . . .

On the domestic front, the trail toward Triple Crown heats up in California with Flying Paster off from the extreme outside in Sunday's 42nd Santa Anita Derby for 3-year-old thoroughbreds. Reckoned as perhaps top challenger to Spectacular Bid in the May 5 Kentucky Derby, et seq., Flying Paster (pronounced Pay-ster) faces nine rivals over 1 1/8 miles and tries to show his defeat in the San Felipe Handicap this month, after seven straight stakes victories, was just one of those things.

Old Senator Del Usner, 34, made the grade as a spring tryout and won a contract with the Phillies for a 12th year in the majors, but Ron Blomberg, 30, a career .293 batsman, was placed on irrevocable waivers yesterday by the Chicago White Sox.

The onetime Yankee phenom (No. 1 choice in the 1967 baseball draft) ran out of unlimited potential after a hideous run of injuries. He got to bat only twice in two years, 1976-1977, but the White Sox took him on for 1978 on a four-year, reported $600,000, no-cut, no-trade contract. Aches and pains prevailed again, and he hit .231 in only 156 times up last season; this spring, a minor groin injury restricted his training camp activity. Blomberg was asked to report for Triple-A duty as Des Moines, refused, and owner Bill Veeck bowed to the decision of his manager, Don Kessinger, and coaches.

"I guess," Veeck groaned, "Ron and I are the only two people in the country who think we can still hit. I'm poorer but not wiser."

So on your (post) marks, already, ticket orders for 1980 NCAA finals must be mailed April 2 - no sooner - to 1980 NCAA Baseball Finals. Market Square Arena, 300 E. Market St., Indianapolis, Ind., 46204. Send certified check or money order for either $60 (two sets for the March 22 and 24 sessions) or $120 (four sets, the limit), payable to "1980 NCAA Basketball Finals." That gets you in a drawing, date to be announced; money back if you lose, ticket if you win.

The crazy mascot craze:

Washington's NASL team is issuing a call for enthusiasts of all ages and shapes to audition throughout the next week; candidates to react spontaneously to hypothetical game situations, also do a 30-second free-form routine (Call Andy Dolich, 544-KICK, for a shot.)

Comes the Cosmos visit to the stadium Sunday, April 8, in the presence (the Dips hope) of an invited 50-75 mascots from all over, the unveiling (a costume secret meanwhile) of . . . the diplomaniac!