The past is big business at present and is likely to become even bigger in the future — at least in Abingdon, where the lovely County Hall, described by the architectural historian Nikolaus Pevsner as England’s grandest free-standing town hall with an open ground floor, is about to have £3.5m spent on it. Not before time, either, since I gather the roof has been leaking for years, making it hard to display artefacts in the attic rooms beneath the lead and timber framework — which has proved awkward as the Hall has been a museum since 1912.

The County Hall, so called because Abingdon was the county town of Berkshire from about 1556 (when it received its town charter from Mary I and her husband Philip of Spain) until 1869, when it finally lost out to Reading, was built in 1678-83. The architect, or “undertaker” as he was quaintly called, was Christopher Kempster, the master stonemason from Burford who worked with Sir Christopher Wren in the rebuilding of St Paul’s Cathedral after the Great Fire of London in 1666.

Experts agree that even without the known association with Wren, the building is so good — with its open ground floor to accommodate a market and its beautiful Sessions Room above for the Assize Court — as to show the hand of the king’s architect in its design. The windows, for instance, are reminiscent of those at Wren’s Trinity College Library in Cambridge. Kempster sold stone for the rebuilding of London from his Cotswold quarries, notably at Upton. The stone used at the lower level of County Hall probably came from there; that used above probably from Headington.

Poor old Abingdon, it has had a roller coaster ride through history but architectural fragments of its past, vast importance crop up all over the place. It claims to be England’s oldest continually inhabited town, having grown up around the gates of the Abbey — which was founded in Saxon times (possibly 7th century) but dissolved in 1538 and hung on to its county town status until the railway age — when Abingdon was relegated to a branch line whereas Reading prospered on the mainline.

Then in 1974 Abingdon suffered the indignity of being taken out of Berkshire altogether after historic county boundaries were changed under the Local Government Act of that year. The County Hall was built as part of the town’s successful bid to keep the Assizes rather than see them depart for Reading. Famous cases include the trial of Dennis Collins, found guilty of throwing a stone at William IV at Ascot Races in 1832. His death sentence was later commuted to transportation for life.

Throwing things seems to be a tradition in Abingdon, and among the museum’s exhibits are carefully preserved bread buns. These have been gathered up at the various occasions when mayors and other figures of authority have seen fit to throw them at the populace from the roof of the County Hall (or perhaps from the proclamation balustrades which, until alterations in 1852-3, adorned the front of the building).

This bun-throwing habit, apparently unique to Abingdon, dates at least from 1760 when a John Waite recorded that he caught one during celebrations for the coronation of George III.

But if the mayor mocked the populace by throwing buns at them, the populace has long mocked the mayor back. Only last Saturday, a Mock Mayor of Ock Street was installed during a ceremony dating back at least to 1700.

In that year. there was an ox roasting in the Market Place and a battle for the ox’s horns ensued between people living in a street called the Vineyard and inhabitants of Ock Street. The latter lot won and as a result every June on Mock Mayor Making day horns marked with 1700 are paraded about the town by Morris dancers.

The museum will close in the autumn for renovation work and reopen in 2012. A full programme of fundraising events is planned by Abingdon Museum Friends. Further information is available from www.abingdonmuseumfriends.org.uk.