Cyclicals paced gains ahead of the US central bank's policy announcement, possibly on hopes that policymakers might rein in their outlook for further interest rates.
Defensives led gains on a down day for the FTSE 350.
Defensive areas of the market such as Tobacco and Pharmaceuticals came under a bit of selling pressure in the middle of the week following their recent run higher.
Industrial Metals&Mining, Big Oil and Life insurance lent their weight to the FTSE 350's advance at the start of the week.
General Industrials and Retailers led gains on the FTSE 350 in the middle of the week, but similar gains for some of the more defensive segments of the stock market, such Electricity and Tobacco, betrayed latent caution.
Autos&Parts and Travel Leisure paced losses in a down day for the FTSE 350 as the war in Ukraine dragged into its 138th day amid reports in recent days that Moscow had begun to mobilise reservists.
Autos&Parts, Industrial Transportation and Construction stocks paced gains in the last session of what turned out to be a slightly positive week for the FTSE 350.
A motley assortment of sectors led the FTSE 350's bounce on Wednesday despite the release of weaker-than-expected economic data and the political ructions in Downing Street.
Oil&Gas and Industrial Metals plummeted on Tuesday amid a downdraft on the wider FTSE 350, despite a large move lower in sterling.
Big Oil helped drive a bounce on the FTSE 350 at the start of the week after analysts at JP Morgan sounded a wary note on plans now under consideration in the West to impose a price cap on exports of Russian oil.