We have a couple of standard lamps with an uplighter and integrated flexible reading lamp. Both foot switches for these have failed in the same way - all the moulded plastic "lugs" in the top of the switch, to which the base is held by four screws from underneath, have sheared off (these aren't the only plastic mouldings I've had fail in this way; I once tried to pull a Nicad charger out of a 13A socket, only to find I had the top cover in my hand and all the live electrical connections on the base touchable!).
What is odd is that it is very difficult to find replacements for the "double" foot switches. There are any number of single switches available - and I guess I could use two of these for each lamp - but a double switch is as rare as hen's teeth. Neither Amazon nor Ebay appear to list them, and nor do the usual electrical suppliers such as TLC. I did find a couple of UK suppliers selling what appears to be the same switch for the same price and P&P:
But that was it; I wonder why they are so rare when there are many lamps with double foot switches still being sold.