Keith Waudby asked for a valuation on this Roman coin of Marcus Aurelius. It’s a sestertius, which is a denomination that turns up infrequently in comparison to many others. The few that I have seen as detecting finds have been almost invariably in poor condition.
On the obverse is a legend reading IMP M ANTONINVS AVG TR P XXV around the laureate head of Marcus Aurelius. On the reverse, in five lines within a laurel wreath, is PRIMI DECEN NALES COS III S C. In volume II of David Sear’s Roman Coins and Their Values a variety (with a different obverse legend) is listed as number 4992. The type was struck at Rome in AD 171.
This sestertius is missing a few flakes of metal from its edge but would grade VF and has a very good portrait on the obverse. In its present condition I would set the price range on the coin at £150 – £200.