Hi Keith,
I followed mdj8 in his advice on the cross referencing of this part after also getting the VSC and check engine lights on, code p1155 being my problem, lucky for me this indicated the front sensor so easy to get at!
I replaced it with the Denso DOX-0243, which whilst early days for me does appear to have solved my problem also, so my grateful thanks to mdj8 for his efforts in achieving this cost saving solution to what appears a common problem.
I suppose Denso have to maintain an allegiance to Toyota so that premium pricing can be maintained for the Lexus brand but I can confirm they do both have Toyota stamped on them and look very very similar!
Finally I can also recommend sparkplugs.co.uk as offering a reliable and prompt supply solution if you should choose to go down this route, good luck.