Sleep in rate for carers.

[Iownabigvase]

Hello. I'm just wondering if anyone can shed any light on this. Sorry if it's confusing but I'll try and keep it simple.

I've worked for my current employer for around 7 years in total. I took 1.5 years off around 3 years ago for maternity leave then came back. Before I left for maternity we were getting paid a flat rate of £20 for a sleep ins then it went up to £7.83 (minimum wage) per hour by the time I came back. I actually officially left the company during that maternity leave (so off the books) as I couldn't do the sleep ins due to having dd so wasn't suitable for the post. All other staff who have been and stayed here got a back dated payment because HMRC said the £20 flat rate had been too low.
Because I left then came back I didn't get this. Now I've just heard from my colleague that they are now back dating this again and she said that she's getting yet another backdated payment (she got one a few years ago as she has been with the company for 11 years and never left)
Apparently there's a letter fpr staff "coming out" soon and she said I'm due this back dated payment. I did 2-3 Sleep ins every week for 2.5 years back then.
I don't want to get my hopes up but could really do with this money.
Will I be due this or because I left then came back will my entitlement to it wipped? Or because I'm employed with the same company, same service etc will I have a case to get it back dated?
Thanks.