A-ha! I think you are looking for what Steve Nison calls tweezer reversals but I have never heard anyone else seeking them or even referring to them in their TA. Nison says -
'Tweezers are two or more candlestick lines with matching highs or lows. They are called tweezers because they are compared to the two prongs of a tweezers. In a rising market, a tweezers top is formed when the highs match. In a falling market, a tweezers bottom is made when the lows are
the same. The tweezers could be composed of real bodies, shadows, and/or doji. A tweezers occurs on nearby or consecutive sessions and as such are usually not a vital reversal signal. They take on extra importance when they occur after an extended move or contain other bearish (for a top reversal) or a bullish (for a bottom reversal) candlestick signals.'
I'd be surprised if these turn outo to be significant enough to be worth looking for. Scanning back over the FTSE chart I can't see a true example. There seem to be passable examples on the Dow chart, but that's more likely because the way Dow data is charted it hardly allows any gap between close and subsequent open: so if the close is the high of a Tuesday, Wednesday will likely open within 0.5pts of the close, and if the index falls from there, the two closes match closely enough to be a tweezers. OK, maybe that's significant for your trading style, but it must be quite unique if so.