A truncated session saw London’s benchmark index break through the 5,600 level for the first time in over four years.
Having touched 5,608.2 in early trade, its highest intra-day level since August 2001, the FTSE 100 ended the session at 5,595.4, 1.6 points lower.
The FTSE 250 jumped 32.8 points or 0.4 per cent to 8,759.8, another all-time high.
But with only 600m shares traded there was little appetite for dealing.
With only a handful of trading days left this year, mid-cap stocks look set to eclipse their blue-chip peers.
Since the start of the year, the FTSE 100 has gained 16.2 per cent while the FTSE 250 has jumped 26.3 per cent.
The continued rise in the price of copper helped BHP Billiton 1.3 per cent higher to 925p and Antofagasta up 0.9 per cent to £18.53.
AstraZeneca, the Anglo-Swedish drugmaker, rose 0.6 per cent to £27.95 after it agreed a deal to buy Kudos Pharmaceuticals, a privately-owned UK biotechnology group.
Marks and Spencer gained 1.1 per cent to 498½p as it continued its stellar quarter. M&S shares have risen almost 40 per cent in three months on hopes of a recovery, to the annoyance of those short on the stock.
Housebuilder Persimmon rose 1.9 per cent to £12.75 as the Office of Fair Trading said it would not refer its offer for smaller rival Westbury. In the same sector, George Wimpey, which is widely seen as a takeover target, gained 2.6 per cent to 487½p.
Wolverhampton & Dudley Breweries rose 1.7 per cent to £12.85 as UBS raised its price target on the pub group from £13.70 to £15.
Rival Greene King slipped 1 per cent to 746½p as it was downgraded to “neutral” by the same bank.
There was some profit taking in defence group BAE Systems, down 1.7 per cent to 378½p. Its shares rose sharply this week on news that its Eurofighter consortium was poised to win a multi-billion pound fighter jet deal with Saudi Arabia. Cazenove upgraded BAE to “outperform”.
Interactive media group Yoomediarose 10.7 per cent to 7¾p after betting and bingo group Gala bought its Avago gaming channel brand. Yoomedia said it would retain an interest in the channel.
Hardy Amies gained 7.4 per cent to 5½p as the Savile Row haute-couturier said it had raised working capital and held “positive discussions with a strategic partner to deliver the next stage of growth”.
Investment group Nanoscience gained 12.5 per cent to 13½p as it gave a positive assessment on the progress of Toumaz Technology, the Imperial College spin out company it bought last month.
Mincorp rose 33.3 per cent to 2p as it said it was ready to begin boring at its Mount Cadig site in the Philippines.
Radstone Technology, a technology supplier to the defence and aerospace sectors, lost 16.4 per cent to 247½p as it said second half deliveries would be less than forecast. Cazenove cut the stock to “inline”.
Newport Networks, the telecoms equipment group chaired by Sir Terry Matthews, the billionaire founder of Newbridge Networks, slumped 26.4 per cent to an all-time low of 19½p after it proposed a share placing to raise £15.5m. Shares in the group, which warned on profits in September, peaked at 160p in April.
Trafficmasteradded 8.6 per cent to 28½p as Colin Walsh, non-executive chairman, bought an additional 100,000 shares.
Lloyd’s insurer Hardy Underwriting rose 4.6 per cent to 229½p even as Peter Hardy, former chairman and chief executive, sold the majority of his holding in the company. Other board members, including chief executive Barbara Merry, picked up stock.
In new issues, Venue Solutions, a provider of venue management technologies, rose 3.8 per cent to 27½p on its Aim debut. The group, which works with clients such as Fulham football club and the Scottish Rugby Union, has a market value of about £8m.
Asos, the internet retailer, lost 4.2 per cent to 45½p as the shares resumed trading.
The stock had been suspended on fears that its warehouse had been damaged by the explosion at a fuel depot in Hemel Hempstead this month.However, Asos said the incident would not affect profits. “Given our fears that the effect of the blast would be to make the Asos warehouse permanently inoperable, this announcement is reassuring,” analysts at Charles Stanley said