Letters from previous employers

Hi all,
I am going for ILR appt soon at Sheffield. My time line is WP-1yr, HSMP & Tier 1 -4yr, with 3 employers in all, First was WP, Second was partly on work permit but changed to HSMP inbetween.
Most recent employment is over 3 1/ yr now, initially HSMP now Tier 1, this is a permanent job.
My question is if I need letters from the previous two employers. I do have the original WP letters from both. as well as pay slips.
Thanks for help
Best regards

Hello,
Its only from current employer

Deep..