Pocket plates

[840aj]

Any suggestions where I could get pocket plates for old steel block cushions? I bought the cushions on eBay without plates. The seller said they were Burroughes and Watts but there are no markings to confirm this. They are the single pin type bolted from underneath. I bought some Peradon ones from a supplier but the don't fit properly.
Any suggestions would be much appreciated.
Andy.